We had a similar problem with dots at the end of folder names. A user created a folder inside a synced library on his mac. The mac-client is syncing the folder without errors, the web-gui is showing the folder without errors, but the windows client is unable to sync the folder localy.
The same problem is there with a colon inside a file- or foldername! Mac and Linux users can create such files and sync them to the server, but windows users will never get those files sync to their desktops.
Maybe it’s possible to show a library with invalid file-/folder-names as “synced with errors” inside Seafile client?
The client does show a warning message during the sync for a short time,
but afterwards it shows “sucessfully synced” If you have large amount of files you could easily miss the error.