The revisions-overview form for translated nodes shows a current revision only for the language the revision was saved in. The revision is listed correctly, but it's not marked as current.
Visit the revisions tab for a translated node in different languages. Only one of the translations will have the "Current revision" line. Save a different translation of the node, and you'll see this last language will be the only one with the "Current revision" line.
Imitate what was done in Drupal core over 3 years ago, in #2938947: Always list a "Current revision" for each available content translation → .
Needs work
1.0
User interface
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.
For this to be reviewed and accepted, please review https://git.drupalcode.org/project/diff#contribution-guidelines. Since this is a decidedly old contribution, it likely needs a reroll/rebase. Additionally, we'll need some tests.
Postponing this on 📌 Consider showing all revisions on the revision overview Active once that is in we can apply the same logic to Diff.