If the Austrians (somehow... the French had good commanders and the Austrians had bad ones) and the British beat back the French, would the Austrians ask for Lorraine back? Maria-Theresa's husband gave up Lorraine for Tuscany and France now controlled Lorraine. However, a victorious Austria is in a position to demand it as compensation for swearing to agree to the Pragmatic Sanction (and not honoring it).
Of course, if they are doing well on the Rhine front, they'd probably divert troops to Sileisa where they will just get picked off in detail, but let's say the Bohemian front goes like OTL in TTL and the Austrians and British stand on both Lorraine and French soil they have no intention of taking whatsoever.
I mean, the Pragmatic Allies had a numerical superiority of troops on the field when the Netherlands campaign began, as well as some defending knowing the terrain. If they defended properly (which they could, as I said leadership problem), they could have made a decisive counterattack on a retreating army. So would they ask for Lorraine back, or just $$$?