The Humongous games on Steam do have multiple languages, the ones I checked have English, French, and Dutch available in the 'Language' menu of the game's properties, some also have German.
And yeah, these games are pretty small, all Humongous games together should easily fit on a Switch gamecard. And since they all use a similar engine, once you've ported one to the Switch, porting the rest shouldn't be that much more work. Maybe they're saving other games for a second release?