Hi! First off thanks a lot for posting and being a user for years. Nice to see a new post after years of silence! :)
I haven't developed the app or created any updates for quite a while. I also have not tried installing any of the newer CFW binaries so I have no idea what may have changes to cause those problems. Any thoughts from other PSPSeq users? Do other older apps run OK? One thing to try is to just load in a single simple synth and see if that plays without errors. It sounds like the PSP is getting overloaded with things to do and PSPSeq is lagging behind, but it could certainly be something more subtle than that.
FYI I've been doing some Android programming as a part of my job. I am somewhat tempted to write an app for that platform for music/audio manipulation but time is just too tight right now. If I do write something I'll certainly post about it here and it will undoubtedly have that wonderful aliased crunchiness that help make PSPSeq what it is.
Lastly, as always happy to hear any music people have written with PSPSeq. Seeing what people eek out of the program is one of the best parts of throwing something out there.