I always try to buy used files whenever I go to fleamarkets. I restore them just like you did. After that they are as good as new. You can never have too many files. Small sizes especially. It is also a nostalgic trip to a past of American manufacturing. Some brand names that I never heard of.I got myself a pair of old files, rusted and all. After some clean up, I dipped in vinegar for 1 day and clean up some more, then another half day, then cleaned it up. It looks pretty good and cut well when I tried it. Not like new, but I think it's very usable.
Yes you can ! Nice job on the files .You can never have too many files