Hello. I see that you haven't yet received a reply. I am unsure of your location, so cant really comment on specific brands. You are correct, there is often comment about guns being over lubed. What needs to be considered is that manufacturers apply sufficient lube to protect the rifle as it may sit on the retailer shelves for some considerable time. Excess lube if often identified when a rifle "diesels" but in more cases than not, firing pellets will cause the lube to burn off. This could take a few pellets or s significant number - but the lube will nine times out of 10 burn off.
So getting to your question about the piston seal lube - I do lube the spring but I don't lube my piston seals in any significant way. The seals are manufactured of a material that does not require lube other than a very very light covering. Any grease is ok. The reason for moly lubes is that the steel absorbs the molly - but not the piston seal which is not made of steel.
Sorry, rather a rambling reply, but I hope it helps.