I've been playing Koudelka (NSTC version) on FPse on my Samsung Galaxy A3 for a while now. Had no issues while playing disc 1 or 2, aside from audio cutting out briefly during cutscenes (which is a known thing for emulating this game, even playing it via the disc on PS3), and one random freeze during a battle.
However, I've just started disc 3, and I've been having issues with areas seemingly not loading in, just giving me a perpetual black screen. Around the start of the disc, you go into an area with a waterfall, with an area at the back with some stairs. After going down these stairs and trying to go either left or right, the glitch occurs, the screen goes black but audio continues. The game will also freeze if I encounter a random battle in this area, again with the audio still going.
I tried loading my memcard save in ePSXe, and managed to get past these areas just fine. I made a save in the area that would just keep giving me a black screen, loaded this save in FPse, and all seemed fine, until I left the area again and went back down into it, and I got a black screen again.
Not sure what's causing these issues, I've tried fiddling about with the settings to no avail. Don't think it's any issue with the ROM itself because I'm not getting these issues with ePSXe, though I'd rather not play it on there as I get graphical issues during battles on that emulator.
Edit: I think I've fixed this by enabling "dynamic interpreter" in the system settings. I'm no longer getting black screens going between areas, though I haven't played it extensively yet so not 100% sure there's no more issues. I checked back on disc 1 and 2, and dynamic interpreter wasn't enabled for them either, so I have no idea why they worked fine without it and this disc doesn't.
Seems I'm having issues with the settings in general in FPse, the general/default config doesn't seem to apply to games, I have to set them manually for each game, and a lot of system settings simply won't save either (thankfully dynamic interpreter does). I have "boost mode" active for one game for whatever reason, but no amount of me disabling it and quitting out of the game makes it save that setting, it's always enabled again what I start it up again. Don't remember this being an issue before, not sure if the latest update back in December messed with this or not. I haven't been using FPse a lot since then, so I haven't really noticed previously.