The heck?!?! I can't believe I never looked in Alternatives!!!
I've written a macro that will work, but there's one hurdle I haven't been able to overcome yet.
The ProjectData file is encoded in a way that KM can't read. If we can fix that, we'll have a working plugin test!
We'll also have to make sure the most recent alternative is used to draw the data from, but I think that's doable. This encoding thing isn't something I've encountered before.
It appears that one has to alter the file encoding for it to be read, but of course that isn't possible with this file. We could copy it as a temp file and change that, but I don't know how to change encoding in the first place. So near yet so far!
I can already imagine how I'd use this to batch-test project files... by adding Finder tags if the plugin is found! 