Hello and welcome to the NC-community-forum where everyone tries to help everybody else…
a bit of searching the forum for similar problems/tasks ahead of opening just another thread would have been nice and helpful. Like you might have found this existing thread (linked to several other threads) for the same question: Mirroring of two nextcloud server
That’s regarded being a professional demand and no more homeuser-setup. So first and foremost you should apply for a quote from NC GmbH for professional support.
But you’re free to ask your questions here on the forum as well, of course. But most probably you won’t find much ppl with a setup like yours.
Good luck!