I don’t know that I can answer your question, sorry, but something you said confuses me.

• file storage/syncing from a central server (so Syncthing is out) … While working absolutely fine for sync between different devices (have it in use in a different scenario), the peer-to-peer nature is unsuitable for what I’m looking for

Why? I think you missed describing a requirement, because there’s no reason SyncThing can’t do “for syncing from a central server.” Do you mean one-way, or one-to-many, or what? What, exactly, doesn’t SyncThing do that you need?

I believe SyncThing is not the right tool in many scenarios, but I don’t understand these bullet points.

For one thing, SyncThing is only peer-to-peer if you set it up that way. You can absolutely define a “master” simply by only connecting the “clients” to the master. It’s an utterly arbitrary distinction, but the clients won’t know about or communicate with each other unless you explicitly pair them with each other. This is how I have our phones set up: each one is paired to the central server, but neither is an introducer nor knows about each other. We have one directory that the server has shared with both phones, and several directories that the server shares only with one or the other phone. I even have the server connected and sharing all of the directories with a second, backup server that neither phone knows about.

Again, I’m not pimping SyncThing; it has weaknesses, the biggest one being any lack of sophisticated merge ability. I wish it had a plugin system where, for each for type, in case of conflicts it would call out to some external merge program; rather than just throwing up it’s hands and going, “well shucks, guess I’ll just spam a bunch of sync conflict files”. And it can be annoyingly slow recognizing changes and syncing; it would be a terrible choice for any sort of pair programming file sharing.

But what problems have you encountered with it, for your case?