That's a good question. While my database side tells me to normalize data, and never have any dups (e.g. have a "river master relation" that includes the river names in every language, wikipedia, wikidata, and any other shared tags that apply to the whole river), I understand there are problems with many data consumers to process super relations, so data needs to be duplicated. So I think the wp/wd tags should be on both rels (sadly), and maybe an automation rule should be set up to verify that the wikidata tag is the same. It is not as critical to have WP tag identical - most data consumers should translate the wikipedia tag to their user's primary language using wikidata (I actually think that at some point we should get rid of wikipedia tag outright, if it represents the whole object and not a part of it. See osm.wiki/Proposed_features/Wikipedia_tag_types

hmm, sounds like a bug for the iD devs :) Can you file it with the above explanation?
https://github.com/openstreetmap/iD/issues

Strange, this edit only added wikipedia tag: http://osmhv.openstreetmap.de/changeset.jsp?id=47082371

Hi, thanks for adding wikipedia tag. Please install "wikipedia" plugin, and use "fetch wikidata IDs" too - it will add both wikipedia and wikidata tags for you. Thanks!

Hi, please use "add field" when adding wikipedia tag (from dropdown). This way it will automatically add wikidata tag too. Thanks!

Hi, please use "add field" when adding wikipedia tag (from dropdown). This way it will automatically add wikidata tag too. Thanks!

Hi, thanks for adding wikipedia tag. Please use "add field" (dropdown) instead of adding tags directly. It will automatically add wikidata tag too. Thanks!

Hi, thanks for adding wikipedia tags. When you add them, do you use "tags" or "fields"? Because if you add "wikipedia" __field__ (from the dropdown), it will automatically add wikidata as well. Thanks!

Please check the fixme in changeset/47060050

Hi, I deleted Monocacy Creek Area - that way is clearly broken, and I don't see it on satelight.
Please restore and fix if possible: way/63521337

Hi, I deleted Monocacy Creek Area - that way is clearly broken, and I don't see it on satelight.
Please restore and fix if possible: way/63521337

Church tags look highly messed up

Hi, please clarify what this is, and if you have a web site / wikipedia article about it?

Hi, you are right that they need to be more organized. I made a proposal for it osm.wiki/Proposed_features/Wikipedia_tag_types

Also, thanks to wikidata, we can clean up wikipedia tags now (almost 2,000 already done):
https://www.mediawiki.org/wiki/User:Yurik/OSM_wiki_tag_problems

"se" here is not a languagecode, but a code for one of the Wikipedias projects (which are tied to the language code). "se:Hamburgö" is meaningless, because no system will ever show you a wiki article. It doesn't matter if the language code is wrong, or the typo in the name. Whomever added that link made a mistake, and no one checked it. Usually I delete broken links as they don't add any value -- instead they pollute OSM with junk and reduce overall quality. But I also try to find the right link, in any language possible. In this case, I added the very first article that matched description.
Vandalism is to have a broken link added to OSM with malicious intent. Fixing it to any working Wikipedia is an improvement. If you think there is a better article - sure, you are welcome to change it, but calling an act of fixing -- "a vandalism" is irresponsible and offensive. Wikipedia has the "assume good faith" doctrine. Please follow it, before making an accusation.

Replied in, please double check before claiming abuse -- changeset/46604875

Deleting??? Please look carefully, the link was broken -- it used incorrect language code, so I picked the first related article I could found instead of simply deleting it. So no, it is not "abuse from a user", please check carefully before saying things like that.

How is it possible for the water outline to also be a road? Isn't there usually some space between them?

See osm.wiki/Proposed_features/Wikipedia_tag_types

Вот ещё нашёл - https://en.wikipedia.org/wiki/Islet#In_international_law -- "...ignores islets, regardless of inhabitation status" -- то есть для islet не важно если там кто-то живёт.