It bothered me for some days, until I realised that turning off rewind fixed it…
I was trying to run Popful Mail for the NEC PC Engine-CD (image from PD) and it kept crashing RA.
After I turned off rewind everything is back to normal. Several versions of the core give the same result.
Will this be fixed? Some Japanese exclusives really need rewind towards the end 
It’s probably not going to be fixed any time soon, as it requires some esoteric examination of the core, but you could open an issue at the core’s github repo so it doesn’t fall through the cracks.
This is one of the games that has glitches (garbage graphics in cutscenes and will freeze in some of them) in the Fast core, but works perfectly in Mednafen stand alone’s default accuracy profile. Could be the reason it has problems with rewind.