Change the js.topic.deleted_by_author.one and js.topic.deleted_by_author.other to anything the already existing text ((topic withdrawn by author, will be automatically deleted in 24 hours unless flagged)) in Customize > Text,
Add a topic as a regular user.
Delete the topic as a regular user
Expected to see the updated text, but (topic withdrawn by author, will be automatically deleted in 24 hours unless flagged) is displayed.
Issue could be in this code:
It seems that js.topic.deleted_by_author.one or js.topic.deleted_by_author.other are not referenced here, but only js.topic.deleted_by_author, which does not exist in locales config.
This is occurring because the self-deletion text is translated and stored on the server as a post revision. The translation change will only take effect for newly deleted posts.