Inside any LocalisationTable.asset it has keys & value for not only the current schema but old keys that are no longer used. It doesn't cause any behavioural issues but the data could get very bloated.
Suggestion
Make the "Find / Refresh" button into "Find / Refresh / Validate" and have it purge all dead keys from all the tables it finds. Alternatively a dedicated button, but after this button is clicked we have access to all tables and the schema.