Time tracking is an interesting topic. At my company we addressed this by having a Herald WebHook hit our internal server whenever activity we're interested in tracking happens. Our internal server tracks these activities from multiple sources (not just Phab/Phorge) and users can go in to see all their activity linked up and input the approximate time spent on those activities.

I'd definitely love to see this later. I MIGHT be able to get to this later.

This looks pretty great! - I think T15030 is the general covering task for Extensions