Ayeeee thank you so much for your kind words! OOO yes being able to have it color swap over all open files would be great actually. Currently it does the current file but i can def take a look at adding support for multiple files :) Ill add this functionality to a feature request for the next update.
A little workaround to do this currently would be to add each of your sheets to a new layer and then export as it can work though multiple layers at a time. This should work best if your sheets are the same size ofcourse but when I implement multiple files they could be diffrent for sure.
Thank you again for your support on my tools and I very happy to see your comment on this!
Edit:
I've created a feature request for multifile support which would end up being slated for Color Swap v1.2.0 once implemented :D Any progress can be tracked over on the issues/feature request page:
https://github.com/CarbsCode/CarbsAsepriteExtensions/issues/41