I've only ever played the game on OPL and never had any issues (after turning Mode 6 on), outside of crashing the game on the first Ark stage after hitting a specific enemy in a specific way. This is getting completely off topic, but I remember when I bought the FMCB Memory Card. My friend had a PS2 he let me borrow, which I'm guessing was because of how much I talked about Klonoa, so I just messed around on the menu for weeks, looking online to shop any time I could. After searching hard and competing on Ebay auctions for Klonoa 2, I ended up caving and just buying a FreeMcBoot card. Oh christ the ensuing days were painful. It shipped in two days, but my family went on a week-long trip, and I had Klonoa 2 lodged in the back of my mind the whole time. Then I finally got back home and put the card in, but despite having OPL pre-installed, it would not work. I messed around on it for a while, and I distinctly remember crying in my pillow. Then I decided to turn it back on and mess around in the file explorer, and I booted up OPL from that explorer. And my games just so happened to show up. Then playing it for top to bottom without getting up a single time, just IN the experience. When people ask me why I love Klonoa 2 so damn much, well, it's right there. I've never felt the same way with... anything. This period in time is the best I have (and like will) ever experience(ed).Oh, then waking up the next morning and playing Kingdom Hearts for the first time, at 5:00AM, then going to Walmart for a Veterans Day Scouting event, and rushing back home to replay Klonoa 2. That was the life! Damn, it's weird saying that I was hyped for a game that was already out for so long (and one this obscure), but that was one hell of a time. Oh, sorry. Guess this wasn't exactly the best place. Well, I guess that can be your slice of Klonoa for the Holiday season... in the Emulation thread. How did I get here?
For an actual comment, I wanted to mention that documentation OPL compatibility issues on the whole isn't exactly good. But for Klonoa 2 in particular I feel like it is almost always off, and the same thing is for K2 compatibility on the PS2 Classics emulator for PS3, which is horrendous btw, never play the game like that. I've never played the game on an PS3 FAT, neither have I played it on the PS2 Classics emulator for PS4 (as I do not own a PS4), so I can't exactly comment on those. But given the let's just say problematic PS2 emulation that's been seen on the PS5, I'm guessing it won't be very great there.