Are there any posts or anything about the languages in Killigan's world, any file alphabets? 

And will there be any puzzles like the Unown puzzles in the future game? Thank you.

At this time, there's no set alphabet for the in-world languages in this game. Maybe later on that'll be revamped, but for now, it's treated as seeing the world through Killigan's lens: He understands New Bovolian very well as his native language (equatable to our English), while Skrilzian (writing in the style of the image below) looks incomprehensible to him. Both phonetically sound the same, but are written differently.

Sorry if this kinda late but that sounds really interesting if that happen! I’d definitely be down for a revamp if it happens; having a concrete alphabet to decode would add such a cool layer to the game.

By the way, since you mentioned Skrilzian sounds the same as New Bovolian but just looks different, what does the sentence in that image actually say? I’m curious if it’s a little easter egg or if not, well it become the first one that got translate.