Well @notaz is still active right here on these boards. And he is still developing awesome software. And he might very well read this. But I am not so sure there is much he can do about the last glitches or even has the time.
Oh ok, no worries. It seems that PicoDrive 1.91 is the final version on all plateforms as I don't see newer ones on GitHub project, right? Would be cool if he updated it again one day to fix the last issues (the one I listed, especially the worse performance on Sega-CD and maybe improve existing things)!