That's not the expectation here. The key name:etymology:wikidata is correct on each individual way, and just because a tag has been accurately placed on a nearby way or relation does not somehow make it incorrect to attach it to another way.

Regardless of whether MapComplete should recognize name:etymology:wikidata on relations, it is correct to attach the key to individual ways as well. I would appreciate it if you undid your reversions.

Yeah that doesn't make the tag incorrect on the individual ways though. And, some data consumers, (like MapComplete, which I used to add the tags) don't recognize the tags when they're only on relations. I don't think these reversion are correct