It refused a few files with unusual characters in their file name, so you’ll want to periodically check the logs, as it is stricter than the host OS. Apart from that, all good
Do you happen to have a list of these unusual characters ?
It seems to be anything which isn't either ASCII or UTF-8. My father's PC had files written by old versions of OpenOffice (when it was called StarOffice), with "native" names but before his PC was set up to use UTF-8. Early versions of Syncthing didn't have problems with those files, but later versions refused to back them up. I had to rename all those files one by one to get it working again.
If you ever have to do to this again checkout convmv - this can convert for example latin1 encoded file names into utf8 encoded file names.