Writing this from an M1 machine. I didn't send an email because I had read about the licensing issues before the Mac arrived
My biggest use case for a Mac app would be adding words to my list of flashcards, and maybe organizing them better. But I guess that would only make sense after the flashcard rewrite. When I still had an iPad, the daily iCloud sync conflicts were driving me crazy; one of the bigger reasons for tossing the tablet and doing everything on my phone.
(Edit: Sorry for the negativity, I'm not blaming Pleco for the fact that iCloud doesn't seem to sync until _after_ I've used the app for a while.)