Those side bolsters are pretty darn stiff. I’d say that is occurring more from the in & out than sitting. I know I am very cognizant of how I climb in and out for this very reason. Just a thought.
Little trick my buddy told me who is a twenty plus year tech at Ford and works on my car. Slide the seat back when getting out to minimize the wear on the seat getting out.
As far as steam, you can use a small steamers to get them out. I am looking for seat covers as well but csni find any to fit the recaros that I like. Might need to get some made.