I`ve done damage now-and-then since forever. Usually with a fairly mild approach too, it`s almost a complete wild-card situation that makes me wonder whether whatever was done previously (perhaps unknown to me) set the stage for disaster.
E.g., aggressively steaming the leather of an old Benz (service loaner with a zillion miles) went *fine*. No damage at all, came out great. Doing it *less aggressively* to another almost identical one bleached out the pigment. Had that happen a few times with interior plastics too, most recently on the beater-Tahoe where I`d done far more aggressive steaming in the past with zero problems.
E.G.#2- I steamed the carpet of my Mazda MPV (terrible, *terrible* vehicle...) numerous times with zero problems. Then doing it *exactly the same way* somehow melted the carpet. I mean..this was my usual regimen that I was doing quite frequently and then suddenly it was too aggressive and I had damage. What the...?!? "You did something differently"...well, sure that comes to mind, but !oh man! was I trying to be consistent.
It sounds like you`re not being all that aggressive, which is probably good. I just get leery about stuff that seems to go haywire for inexplicable reasons, especially when the damage is permanent.