You won't be able to access the actual diagnostics popup very easily/at all, but essentially all it does is recursively traverse each component under whatever you asked for, and walk through all the qualified values attached to that component (from com.inductiveautomation.factorypmi.application.components.overlay.OverlayUtility import getQualities) and see what's good and what isn't.
There's also some exploration elsewhere on this forum where people walked through the actual binding objects in order to "ask" them for their tag information, but that way has a lot of potential problems. See something like this, or maybe just ask @pturmel really nicely if he's already got something written.
Keep in mind the latter is something that's definitely not supported by IA - if you do something wrong, you could permanently break a window and have to revert to a saved version, so make sure you've got backups before mucking about with internal window properties.