Well how the royals of Leofarinia are seen by the people we know? And who are them?
(And question for my omake, joan is the type to give a hog to somebody eho need it?)
Neutral at worst, highly respected at best, with the average being respected to a sizable degree.
What do you mean by this question?
Hog, as in a pig? Well, I guess, if she had one to give out, although I don't recall having on in the inventory list.
Do we have any info on the world we have arrived in compared to Joan's original world? How big it is? Is it a giant Pangea or multiple continents? etc
The world is Earth-sized or quite near it, if the quick experiments with the acceleration of gravity were any indication.
The maps that you have access to shows a huge, Pangea-like continent roughly equal to the combined size of Asia, Africa, Europe and South American Continents back on earth, with multiple biomes and climates throughout. Leofarinia occupies toward the middle-western end of this continent with the other four hostile nations of note. Beside those five nations, there are plenty of other kingdoms, nations, and other groups and civilizations on this continent. Most of them are not of big concern unless they make themselves a big concern.
Speaking of climates, Leofarinia could be described as "Warm Mediterranean and Italian-like" due to its proximity to the ocean and equator...
Interestingly enough, some rough mathematical calculations with the maps and what you can gather about the planet with your instruments suggests that there is a possibility of an unknown continent sized landmass in existance somewhere beyond the ocean. All of that is theoretical until said continent is discovered, if it even exists. Not to mention ocean-going technology is not that sophisticated enough, nor is there anyone foolhardy enough to undergo a suicide mission like that.
Say have any being any isekai figure in the history of the world/kingdoms also will we get alternative Japanese summoned to this world in the future?
Can other kingdoms summoned their own heroes from other worlds?
The first question has confusing grammar, but I assuming that you are asking if there were any other isekai-like hero or figure in the past in Leofarinia or other nations.
The answer is probably, if Joan Frank and her Foundation's summoning is of any indication. There are records of such figures in the past, but you can't really tell which is fact and which is fiction.
I assuming that the second part of the question is asking if you all will get alternative Japanese summoned if you attempt another ritual like the one that summoned you to the world.
The answer is maybe, but the summoning ritual is not an exact science and there is a possibility that you can summon someone from a completely different plane of reality or universe.
For the third question, I think I already said yes. Yes, the other kingdoms can devote resources to summon their own hero, but it can be an expensive process.