I am not familiar with it...
But I have been told repeatedly not to use anything on a leather holster if you want it to last. Any oils or solvents you rub into it will weaken the leather, possibly cause it to stretch unevenly or even tear.
I would be more concerned with the finish on your Para than the inside of a Galco holster. They are typically unlined, raw leather inside. The lined ones tend to be suede. Neither of which should bother the finish on your pistol.
I would make sure it is clean... if there is dirt or other debris in the holster it might scratch the finish with repeated use.
Or loosen the tension screw a bit at a time...?
I have never had an issue with a Galco rig damaging the finish