The actor table is live on Toolforge replicas, and it appears the foreign keys (e.g. rev_actor) are populated.
The effort involved here is to update our queries to join on actor when we need to filter by username, or use join decomposition, so that we are no longer referencing rev_user_text, rev_user, log_user_text, log_user, etc.
The full list of database changes are listed at T167246.
Affected tools, roughly ordered by difficulty, highest to lowest: