The problem with this is that working copies on both Ubuntu and Mac detect these files as missing, with an unversioned file next to it using the decomposed name.
SVN's xml listing represents ä like %cc%88 but working copies will only handle ä when it's %c3%a4.
This is a legacy issue with svn on mac, and rweb can't do anything about files added from a mac svn client. Use svnkit instead as CLI on mac.