Cornet is an odd choice for a practice partner on grass. Normally she's a poor to mediocre player on the surface.
I don't think you necessarily need a grass court specialist for practice. She was geting into some long fast rallies with Caro and that's what Caro needed. Also - as Fantasy Hero says - Alize has looked good at Eastbourne and pushed Kerber all the way and should have baten her.