At present, we have little to no guidelines with regard to disambiguations. The closest we currently have is https://musicbrainz.org/doc/Style/Artist#Disambiguation_comment, which only pertains to artists. What I propose is we have a general style guide for disambiguation comments, using the current guide for artists as a launching point. Here are some new guidelines that ought to be added:
Disambiguation comments should be entered in English, when possible.
Disambiguation comments should be capitalized as if they were Extra Title Information (ETI).

Discourse threads:
https://community.metabrainz.org/t/style-792-additional-guidelines-for-disambiguation-comments/272314/
https://community.metabrainz.org/t/disambiguations-a-collection-of-examples-and-discussion-of-needs/249806