I thought the same for the longest time. I blame playing tons of runescape as a kid.
I am an American so mold spelling is definitely what I ran into when referring to the fungus. Runescape is British English, so you used moulds all the time in crafting.
Mull is no longer being maintained. IronFox seems to be the go to for mobile now and is what I use. I don’t use syncing so I can’t say for sure, but it does appear to have a sync setup in its settings.