Following up, you should check the new beta for the ninjastic.space website instead. There is a page where you can search an user with auto complete suggestions, so you might find their profile more easily if they have at least 1 post on the archive:
https://beta.ninjastic.space/usersYeah ninjastic.space is another good option for searching accounts and tracking forum activity. It is focused mainly on forum data and makes it easy to look up usernames, posts, topics, and even quoted mentions.
Lets assume an account has no posts, one might still find traces of it through quotes or mentions made by other users. It’s a reliable tool wen it comes to forum data research.