I’ve done a few tests flying through and around cumulus clouds with a Robin DR400.
The up&down drafts are definitely there and the limit of 1000fpm as well, as the Vario showed +/-1000fpm pretty much spot on at the certain points in the cloud. However I would prefer ‘‘the plane would look like a leaf’’, since that’s what would happen in real life. 
(limited) Cloud based up and down drafts are there, but I never noticed any temperature based draft, even with the most extreme settings.
Edit: I was asking in the discord if there are any news about this topic in the alpha testing for the Simupdate 4, but unfortunately there is an NDA. But we gonna see it next week anyway