You're saying 'metadata', but from the context it appears you're talking about parameters, correct?
Specifically, what (meta)data are you hoping to access?
Yes I mean parameters mainly, but also any other information that I might need for manipulation of those parameters.
I want to be able to programmatically apply filter effects to clips in the active sequences... programmatically manipulate
the parameters of those effects, and also programmatically remove instances of the effect.
Ideally I would be able to do this from within an ExtendScript, but if the parameters for my effect were to be exported and imported via an FCP XML I could work with that too.
There is no supported API that provides that functionality.