Thanks for translating this! Quality and translation are good, and I didn't notice any typesetting problems, even if it was done on a phone.
The other group hasn't uploaded to Mangadex in over a year, so I think at this point, they've lost their ability to complain about someone else doing things
Even if it's been 3-6 months, I'd say it's fair to upload a chapter or two, and then more if it goes beyond 6 months. Hell, there's even some manga where 2 groups (if not more) upload the exact same chapter at roughly the same time because they just want to translate it.
So long as the translators enjoy doing it, there's no reason not to have more than one group.