I don't understand the tag feature.
Is is possible to create a tag according to visited pages. If for ex. the visitor have the page 'registration', we could create a tag registration then display all of theses users who went through registration page using the tag filters.
userTrack already supports this.
You can call UST.addTag('tag-value') to assign a tag to a user.
You can read more here: https://docs.usertrack.net/api/client-side-api.html#2-tag-visitors-dynamically
Is this what you were referring to?
We use this with another tool for tagging all visitors who went to the thank you page, looked at about us etc. Very useful feature