You could suggest for the host to go to this page
if they happened to have cloud saves enabled in Steam at the time, with any luck they might be able to recover the files from there.
If they're there, you'd want to place them in their respective correct locations at \Documents\Larian Studios\Divinity Original Sin 2 Definitive Edition\PlayerProfiles
If that doesn't work, could you tell me how many of you there were, and which origin characters / henchmen you were having in your party? My current save is just before crashing at Arx, and I could potentially do something about that to match your party. Possibly.