Greetings,
I agree about acrylics with leather usually only when they are on molded or points where the leather bends (belts, pouches, etc). I have done portraits and the acrylics do seem to stand the test. I have just tested the eco flow paints.
To date my best results remain with spirit dyes and oil dyes, as they penetrate the leather..
Also wanted to add you may experience better lasting qualities with acrylics if you add a top coat, that will "seal the leather".
Cheers
Tom