Yep not even slightly close to every game. It is every North American release but the bulk of what is missing is indeed from Japan and some from Europe that I know about for sure. Not sure what China or some other countries have to offer in terms of exclusives. With the European ones most have had digital releases here so don't think they have a ton of truly exclusive releases. There is a game Spain only got though that I was considering importing and now I have been drawing blanks on the name. Any chance anybody knows? Think it might have been based on a CGI movie or something
Based on eXophase there are 603 Vita games with trophies including PSN releases. Some of those are stackable lists from multiple regions while not all Vita games have had trophies (Such as Deathmatch Village this week) so that isn't the greatest way to try and figure out how many games it has but easier than any other way.