After years this important issue is still there...

On debian jessie one can do: Change /etc/systemd/system/printer.target.wants/cups.service

from PrivateTmp=true to PrivateTmp=false

I don't really see a necessity for a private tmp anyway ...

Apart from the workaround, I would say: why use /tmp for the spool area mount points on the server side in the first place? The directories are being owned by the respective user anyway. Why not use the user's home directory under ~/.x2go? Then this problem would be solved without touching x2goserver-printing nor cups-x2go nor the operating system (see the workaround).

Chris

P.S.: My lack of knowledge: why has the printing be divided in cups-x2go and x2goserver-printing? Why not one package?