I have reworked my original solution such that I only modify the x2goresume-session so as to prevent the options corruption by detecting whether the geometry was specified and, if not, setting an appropriate default value and reapplying the subsequent positional assignments:
134,140d133
< XGSTR=echo $GSTR | sed s/geometry=.*//
< if [ -n "$XGSTR" ]; then
< GSTR="geometry="
< RSTR=echo "$OPTIONS" | awk -F, {'print $13'}
< FSTR=echo "$OPTIONS" | awk -F, {'print $14'}
< LISTSTR=echo "$OPTIONS" | awk -F, {'print $16'}
< fi