Roon has an inbuilt backup feature for the library database which is recommended to setup at the start and you can schedule backups at a time and interval of your choosing.
You cant export an XML but you can export an XL spreadsheet of everything I believe but never done it myself so no idea how its done.
Regarding the re-login issue, as I mentioned this is not normal behavior. I have seen a few similar reports to yours, so we are investigating common patterns among them with the help of our QA team.
I don’t see any updates to this investigation ticket at this time, but I have added your report here as well for when we have an update to share!