Foxx. I suppose you could put the air cylinder some place other than behind the canopy maybe infront as some one suggested. I should consider that myself. Its been my experience with regards to sliding canopies that simple is good.. simpler is gooder..lol..
With my P-47 the canopy frame is Fiber glass wish is stiffer than just a canopy with the frame molded in. And it has a 3 point attachment.... two on the sides and one in the rear.. per the full scale. Most things that get out of alignment do so because of unequal force on one or more members with a limited bearing surface. A way to reduce that is to spread the load over a greater bearing surface.. which is why I suggested attaching the canopy at two points per side instead of one.
Lubrications have their place to help ease things along but they won't make up for misaligned parts very well. Effectively the problem returns after a while so the best thing is to design it such that the moving parts are normal to the plane to start with.. (thats plane as in plane geometry not as in airplane lol).
Les.. you can restrict the speed of air cylinders via several methods. The simplest being a wheel collar and a set screw. Tighten the set screw to restrict the diameter of the air line to your desired speed.
Regards BobH.