For characters, the English version names are used, except for RF3 characters. Major spoilers have warnings before them.
-The continent of Adonea (アドネア) has 2 large nations: the Sechs Empire and the Kingdom of Norad.
-There are also the Repulic of Eucraft (ユークラフト) and the Kingdom of Roland (ローランド). The games haven't mentioned them, except maybe as some character's birthplace.
-Besides these 4 major nations, there are still some other countries.
-All games so far take place in Norad.
-The idea of Kardia is basically like a small town on the Silk Road, where many different kinds of people and information can be found.
-Alvarna is a maritime city relatively far from Kardia. As a city, it's smaller than the capital of Norad.
-Trampoli is a much smaller place, and can barely be called a village. Lots of people come here from Kardia. It's not immediately close to Kardia, but at a reasonable travel distance.
-Sharance is a mountain city.
(EDIT: This sounds suspicious. Kardia is clearly a larger town than Sharance, and is surrounded by mountains, while Sharance has many travellers and a large inn to accomodate them, as well as a mixture of east and west culture reminiscent of the Silk Road. Could it be that he confused the two towns in the interview?)
-Sechs, ruled by Emperor Ethelberd, is pretty large.
-The world outside of RF1's Kardia is largely at peace. The conflict arises there only because it's at the border between two nations.
-Sechs technology and machinery are different from modern concept of machinery.
-To illustrate this, Hashimoto chose two examples: the concept of aether, an idea modern science has rendered obsolete, and Japanese scientists of Edo Period.
(In other words, Sechs science is similar to real world's old sciences like phlogiston, and unlike in real world, their science works
-Humanity originated in Norad.
-Unlike Sechs's machine civilization, Norad has developed a magic civilization.
-Most elves live in their own country.
-Races such as univir and mermaids still mostly only live in certain specific regions.
-The eastern nation is a small island country at the very east.
-It's style should be a mixture of Sengoku Period and Edo Period.
-Its people are samurai, ninja, merchants and miko (priestess / shrine maiden).
(Yeah, the usual cool Japan stereotypes. At least there's no geisha.)
-The elven nation is an island country larger than the eastern nation. The island is covered by forest.
-The elves are led by a queen and several elders.
-Recently many elves are coming out of the island.
-"Earthmates" are people capable of communicating with the land and the spirits.
-In ancient times, an earthmate has all the earthmate powers. In modern times, an earthmate is defined as a person who's inherited part of these powers.
-"Tamitaya" is essentially a magic that returns a person to where he belongs. Using tamitaya on a monster in the human world would send it back to Forest of Beginnings; using tamitaya on a human in Forest of Beginnings would send him back to the human world.
(In typical fantasy terminology, both the human world and Forest of Beginnings are planes of existence
, regions of a fantasy universe. The concept is similar to heaven, earth and hell. But you may already know that.)
-The Gates are just portals linking the human world to Forest of Beginnings. As we know, the empire has developed machines to artificially "shift" monsters to the human world.
-"Rune" is the life force of everything. It's love, the source of life, whatever you call it.
-RP is a real thing.
-When vegetables are raised with care, they emit crystalized Rune.
(Oh no, why must he talk so much about rune? I'd rather think of RP and the effects of rune factories as abstractions.)
-Runeys are something very close to the spirits, capable of gathering the spirits and influencing them. When runeys create a great effect on the environment such as affecting crop growth or rainfall, whether postively or negatively, it's called a "rune wonder".
-While runeys have only appeared in 2 games, they are in fact everywhere. Different places call them different names.
-Ordinary people can see runeys.
-There's no deep reason behind the protagonists' amnesia beside gameplay convenience.
-The de Sainte-Coquille family isn't nobility.
-They are also not merchants. No idea where their wealth came from.
-The head of the families are all big eaters; they don't live in cities because the food is tastier in rural regions.
-They periodically meet each other, but these meetings are more about food than anything.
-Will Max's body grow like his father? No idea, certainly sounds dangerous.
-Lynette comes from an elite family that has for generations contributed soldiers to the empire.
-Lynette tells people she wears a eyepatch because her left eye has been wounded in battle. You may already know this isn't true.
-Cururufa and Ondolfa are childhood friends. Cururufa is older.
-The age difference between them is about 1. However, one unit of univir age is equal to about 19 or 20 human years.
-The Kanno-Cinammon-Candy family is named after sweets in the original Japanese version, as Kanno was called Kanro, which can mean "nectar", and Cinammon was called Drop, referring to liquorice.*WARNING: Rune Factory spoiler*
-Mei is a human. She's also more than 100 years old.
-Mei is in Kardia investigating something about the empire. (Or in words of the character list, "fighting against the empire alone".)
-It seems she once had to follow someone's order, but is now acting on her will.
Really, the game actually provides enough hints that Mei is a great warrior cursed with immortality, wandering the earth. It's not that hard to figure out.
In Freya's words
Mei's past is shrouded in mystery. Evidently, she once had great power which she misused. She often will remind you that power carries responsibility with it.
I said the character list and heroine guide are pointless, but actually buried in them are a few hints about Sharron.
-Sharron is a miko investigating the ruins.
-She is capable of hearing prophecies about the future of the world.
-She's probably not human.
Miko is generally translated as "shrine maiden" or priestess, but in Sharron's case, "oracle" would be a fitting description of her job. In real world history, miko did functioned as oracles. The Zelda series had translated "miko" as oracles. Also, "probably not human"? Why not just say she isn't one?
-Ivan and Raguna are related to Gilbert, the king of Norad.
-Ivan is the king's second cousin.
-Raguna was separated from Ivan in a shipwreck at a young age.
-After hearing rumors of Raguna appearing in Kardia, Ivan disguised himself as a travelling merchant and went to Kardia in search of him.
That's all. He didn't even confirm that Raguna and Ivan are brothers.*RF1 spoiler ends**WARNING: Rune Factory 2 spoiler*
Nothing new here.
-Mana wouldn't get married because she dreams of becoming a teacher, and puts higher priority on this dream.
-All 4 dragons look the same in their infant phase, and are all called Grimoire.
-Kyle isn't of royal birth.
-Kyle's powers as an earthmate is weak. His children are strong.
-The earth script written on the tablets is the writing system of ancient earthmates.
-The ancient magic is stronger than modern magic, but has disappeared along with earthmates.
-Kyle's children has inherited the earthmate blood, that's why they can use it.
-Barret and Kyle's children are currently still working on deciphering this writing system.*RF2 spoiler ends**WARNING: Rune Factory Frontier spoiler*
-In the original Japanese version, Nolan was called Roland. See the names of nations above.
-Iris is not human, but a race "closer to spirits". She's not a vampire.
(Then I suppose there're no vampires in RF universe.)
-The Whale Island used to be a place where they live. The ruins are built centuries ago.
-Iris's race has a very low birth rate, and isn't very interested in reproduction. As a result, they have to crossbreed with humans to keep themselves from extinction. There may be no pure blood left now.*RFF spoiler ends**WARNING: Rune Factory 3 spoiler*
-Her parent race is something similar to phoenix. Among monsters, its rank is very high, close to the dragon gods.
-Hazel and Shinonome didn't know each other when they are young. However, once they met, they realized as single mothers, they have much in common.
-"Shinonome's secret" is a joke. While she used to be a fighter, today she's just a mother, not some secret agent of the eastern nation. And her inn is definitely not a front for Mei and Yue's intel gathering. Mei and Yue are just two travellers who happen to stay at her inn.*RF3 spoiler ends*