We do not have any control over keyframes in FCP – this functionality is handled entirely by the host app, and we cannot affect how it works (or how it often does not, to be precise).

This applies especially to the “Show video Animation” window. From what we know, Final Cut cannot properly operate on or save keyframes when they are modified via this interface – even the most basic functions don't work there (for example: if you delete all keyframes via this interface, cut the clip via CMD+X and paste it in the same place, the keyframes will still be present, as if they were never deleted).

The only solution to these issues is animating everything only via the Published Parameters list.