Meantone version double-flat, double-sharp incorrectly tuned
Double-sharp and double-flat notes do not account for the fact Musescore already tunes them up/down, making those notes in particular 5 diesis too sharp/flat. Cx should be enharmonic to Dd in the meantone version of the plugin, but instead it sounds like Ed. Bbb should be enharmonic to A☨, but sounds like G☨.
Double sharp: Change to -35.48 cents
Double flat: Change to +38.71 cents