Actually I have got the drink potion idle marker working - probably more by luck than judgement, because I don't understand what was stopping it working before - the chap just gazed at the ceiling every time. Oh well.
But the sabrecat problem remains, because the 'idleFeeding' idle is not the sabrecat feeding animation.
No chance

I am overwhelmed with Animations that do not and will not work on an Idle Marker.
Same as horses drinking (in the end, I went for the eating idle-marker ... looks OK ... sorta ...).
Custom Animations: In a few months/years someone will make the community massively happy and release a methodology for making them.