Hey there! Seedvault is indeed not ideal right now for multiple reasons, including reliability and usability. The team plans to completely replace it with a solution that will improve a lot what's being offered today.
One of those improvements will be proper SAF (Storage Access Framework) support, so any cloud service that has file manager integration will work with it, instead of just the NextCloud support that Seedvault has.
I understand this doesn't help you today, but I thought I'd provide some context on what's coming eventually.