How does someone submit screenshots for the community update (without @ing on twitter)
As far as I know Twitter is the only way.
I think Twitter is the only way to go for that. It’s a possibility that Reddit could work also (Wangtime’s art is found there a lot, idk if he tweets them too), so you could try that if you don’t have Twitter.
You can always make a post in Community Creations, as well as Reddit or Twitter noted above.