Currently the guidelines read:
Wikipedia: If possible, link to Wikidata instead, which serves as a bridge for all languages. If no Wikidata item exists, only link to the languages which are relevant to the artist. This usually means the artist's native language(s). The English Wikipedia is always allowed.
I'd suggest instead:
Wikipedia: Wikipedia links are semi-depreciated, meaning Wikidata links should be added instead, but if you don't know how to find the Wikidata link it's still better to add the Wikipedia link than to add nothing. Just try to make sure there is no Wikidata link yet before you add a Wikipedia link. You'll recognize a Wikidata link by it's colorful barcode-icon and the Q followed by a string of numbers as it's name.
- Which Wikipedia links can be added? Please only link to English Wikipedia articles or articles in languages relevant to the subject. This usually means the artist's native language(s).
- What if someone adds a Wikipedia link and a Wikidata link already exists? You can assume they don't know this guideline, because there is no depreciation notice if someone adds a Wikipedia link. So don't downvote the edit - which can be very discouraging - but politely direct them to this guideline.
- How to find the Wikipedia article if it's not linked on MusicBrainz: MusicBrainz pages that have a Wikidata link, but no Wikipedia link still display the first paragraph of the Wikipedia article (in the language you have set MusicBrainz to if available) and below there is the "continue reading..." link which takes you to the Wikipedia article. You can also go to the Wikidata page. There you'll have a list of Wikipedia articles in all languages on the right hand side.
Wikidata: Wikidata items serve as a bridge to Wikipedia articles in all languages, so if you add a Wikidata link you can remove all Wikipedia links in return. Wikidata links are permanent and the set of Wikipedia links they contain are maintained by the Wikidata editors, so we don't need to manually maintain our own set of Wikipedia links.
- How to find the Wikidata link: On English Wikipedia articles it's found on the left side under "Wikidata item". If the article is written in a script you can't read try the second to last link in the 3rd section of links or search Wikidata.org for the title of the Wikipedia article.**
- How to create a Wikidata item: If a Wikipedia article exists, but no Wikidata item you can create one with just a few clicks and without an account. Go to Wikidata.org and click "Create a new item". Select the language of the Wikipedia article you found and copy-paste the article's title. You can optionally add a description. Then click create. Afterwards on the new item's page add the sitelink to the Wikipedia article on the right side. Besides "Wikipedia" click "edit" and enter the language abbreviation of the article (e.g. "en" for English or "ja" for Japanese) and the title of the article (not the full url). Then press "publish". That's it.