@WollieWoltaz: Definitely not, since they are heavily customized unlike this one.
According to VenoMKO (author of Real Editor, mentioned in the
Tera topic), after they've upgraded to 64-bit client back in August, they've changed internal filesystem - and to support those new composite gpks, one should probably rewrite some core umodel parts. Since animation support is planned for Real Editor, it will be better alternative than umodel for Tera, because it's able to re-import assets, supports maps, etc. Besides, old Tera builds are still available in steam, you just need to learn how to download older game builds with depotdownloader.
As for L2, it's just one big mess like PUBGs or something with differences between builds / regional versions / encryptions and so on. And it's UE3 game.