I work with video, often film telecined to video and when grading (colour balancing) the different shots, I need to be able to fix a filter's settings at particular places in time. A lot of Non-linear editors have Basic grading filters, FCP has a number, that can be accessed in the Timeline and with the passage of story time the light and lighting will shift, the grading tools need to change with it.
That Camerabag Cinema is a free standing, external tool doesn't matter; Color for FCP was an external app that talked to FCP via "hand-offs" in XML I expect (I noted someone asking for the ability to work in CameraBag Cinema and FCPX just recently).
Plug-in producers have had difficulty with GUI/work windows inside FCP in the past, the "hand-off" to and from the Apps is tricky for some but IF Keyframes in CamBag Cinema translated to Virtual files like Render files that FCP could access or ............ I don't know how you would achieve it but it would be mighty brilliant - look into the old FCP too, there are many (like myself) who use both but prefer the older version still (keeping a MacPro isolated for it too).
By the way, I purchased CamBag Cine and Photo expecting that at some point you'd start adding Cine specific elements to it!
Best wishes, Philip