Hey! Thanks for answering!
I was taking a look at UndertaleModTool and It's not bad at all.
Adapting textures might be a challenge but I'll manage, pixelated fonts are way easier to edit than regular ones.
But I think I'll have to wait a bit longer since UMT can't edit these new files so yeah...
Here's hoping they update the tool!
Again, thanks for clarifying and have a good day!
EDIT: Nevermind, got it working! Time to test a few things lol