It's professionally translated but it kind of looks like a fan translation because there are typos and stuff. Maybe one of the newer copies (mine is like 5+ years old) has more proofreading though! One can only hope.
I only read the first one because the rest weren't written by the same guy!
Honestly it's my favorite novel though. I just fell in love with most of the characters and the environment. I did watch the live-action movie when they showed it last Otakon which was amusing but not nearly as good, haha.
Yeah, it's from Super Dangan Ronpa 2. There's no translation patch for it but this dude is doing a text-based Let's Play of it. He did one for Dangan Ronpa 1 and it was really, really good. 2 is still updating but 1 is complete and it's definitely worth a read. The best comparison that I've heard for them both is they're like Battle Royale meets Ace Attorney.