I have seen a batch export function mentioned in a few threads here over the years, and wanted to voice my support for the feature. As far as I know, it is possible to access all your .artstudio files at once via iCloud, but other file types are not supported. In my opinion the ability to batch convert the .artstudio files to .PSD for use in other apps is pretty critical to really making this useful, since no other apps natively read .artstudio files. A possible solution could even take shape as a stand-alone batch converter tool on Win/ Mac desktop, if that makes things simpler. You could access all your .artstudio files via iCloud on a desktop machine, then convert them all to .PSD with this stand-alone converter tool for use in other applications.
So maybe the most pragmatic answer here is a simple stand-alone desktop batch converter rather than a combined batch exporter/converter integrated into art studio pro (though that solution would obviously be tremendous and more widely discoverable, if it could actually handle large numbers of files). I seem to remember Lucky Clan developing a stand-alone .ABR reading app for processing photoshop brush library files, this might be a similar task? Whatever the solution, getting .PSDs for large numbers of files out of art studio all at once would eliminate a huge amount of tedious one-by-one exporting.
Thanks for considering this issue!