This kind of reminds me of Digimon World 3 and Lord Archive's Diaries universe, with the characters from all over the world (Lord Archive) being trapped in an online game (Digimon World 3).
How many characters are you looking to write about? Even if you pick one character from each country that you have listed, that's eleven right there. If you had more countries or want to write about groups of characters from all these countries, that's a lot to juggle around. If you also want to develop their Digimon as characters (which, speaking from experience, can be helpful), that at least doubles your character count.
You might want to rethink how many characters you want to write about. Pick a few from around the world that you can develop well enough and write about them. Maybe have a few that know each other and a few that are outsiders but get stuck with the group.
There's not much to say about the plot itself, so that's why I'm focusing on the amount of characters.