There was 2 of these folders in preferences, named as follows

À܇í∑4tøˇ–í√Ë@í∑6–í∑“‰øˇ—uration

Ãzí∑4tøˇ–í√Ë@í∑6–í∑“‰øˇ—uratio

I just found another old drive with 10.5.8 installed. It also has 2 empty folders in preferences, weirdly named, which don't allow jdisk to scan,

,Ÿñ§tøˇ‘∞ñ$ (OSX won't allow me to use this to name a new folder either)

ÁY ïΩttøˇ‘∞ï ( (this one, OSX will allow me to copy-paste its name as new file or folder, but jdiskcat still can't handle it)