AnimatorControllerPlayable etc feedback

Picking up off from here after running into some snafus in the previous version (so the feedback there is from 5.2.1f1). 5.3 beta 4 has fixed most of the parameter issues I ran into there, save one:

A parameter in an AnimatorControllerPlayable controlled by curves in animation clips will return to 0 when no clip is driving it (rather than the parameter's default value).

I'm also having some odd behaviour with clips with multiple curves; it's as if only the first curve is being evaluated. Still trying to nail that one down.

EDIT: further experimentation on the 'multiple curves' problem... weirdly enough, it's like it just seems to hate some of my parameters in particular; parameters named 'inputScale' and 'anim_vZ' work, parameters named 'anim_vY' and 'anim_VBias' are mysteriously ignored (regardless of their being first/second/whatever curve on a clip). I haven't the foggiest clue what's going on there...