So you gave up the idea to get the gamecard reader repaired?
I’m not familiar with Powersaves. As far as I know it stores the saves in a proprietary format and possibly encrypted. If this is true and no special converter exists (could not find any), you’re out of luck with this idea.
Two other ideas:
1. Borrow another 2/3DS system with CFW to dump your saves from the gamecards.
2. Buy the cheapest used O2DS in bad but working condition, hack it and use the savemanager(s). Then sell it again if you don’t want to keep it.