Anyone with Lains mod saves not working and too impatient to wait for new mod. I got mine working by copying some folders from the 11.2 mod and putting them in the game folder in the new version. I didn't overwrite anything.
The folders I copied from the mod were:
fonts
mod
piano
Nothing else
It might just be the mod folder that's needed, but I'm too lazy to check/test as the above worked for me and I don't want to break it now.
See bottom right corner of the below image
View attachment 1080789
This is not guaranteed to work and do at your own risk.
It worked for me and I've been playing the game for a couple of hours without error ... YMMMV.
Obviously waiting for updated mod is the best solution, but I'm impatient.