Sorry for bumping this, but I tried to look for older versions of official Retro Arch and I had no luck.
For some reason the set up I had for the Picodrive core did not load games (it exited to the HBC) even if it worked before, so I tried looking for a, I don't know, 1.9.0 or something (is that version of Picodrive working well?) but I only found 1.9.4, or the 1.9.12 from the official site, and it's true that the sound has issues.
Does anyone have an earlier version of RA that has a working Picodrive core? That's really the only one I care about, everything else I find better on SuperrSonic's Retro Arch. I tried to get the older version from the github but now you get the newer one...