In the meantime I wrote a bash script for this on How can I export multiple spritesheets at once? - #5 by hsandt
but I need to dive into Aseprite Lua API to make it a proper plugin. Also, it’s very simple, also uses hardcoded paths and doesn’t have extra options like scaling.
It would be nice to merge all our ideas into one super script for Aseprite with a parameterable popup, at the end.