Haha, you are in luck! I am reckless enough to try.

I have edited the wiki at https://wiki.openstreetmap.org/wiki/Tag:leisure%3Doutdoor_seating to reflect the most relevant content from https://wiki.openstreetmap.org/wiki/DE:Tag:leisure%3Doutdoor_seating , take a look.

One notable thing missing from both wikis is an explanation of how to map outdoor seating for COVID, e.g. perhaps temporary=yes and/or a special :COVID subtag in some cases.

Thanks Rolf!

The bright idea to try outdoor_seating=parklet struck me this morning, I tried it here, then at your prompting read the German wiki, and noticed that option already exists. I had missed it under “Additional proposed” on the English wiki.

I notice the wiki also shows a parklet in Seattle that was not on the map until (I added it)[https://www.openstreetmap.org/changeset/100123161] yesterday, so just now I re-edited it to best match my growing understanding of how these features can best be tagged.