@megavolts: Please check if your locale is set to a UTF-8 one. You can do this by running locale in a terminal. If it’s not try setting it then restart Insync.
Please also check if these file names are encoded in UTF-8. If they’re not try renaming them then restart Insync.
If these didn’t work please send your logs to support@insynchq.com for investigation: How to find the log files.