RegexBuilder was not successful => it is mostly unused, including by myself.
I think that there are three main reasons:
1. It is a thin abstraction above regex. You still need to understand regex in order to use it, especially with more complex cases.
2. Verbosity doesn't really make the code more clear.
3. Regex is popular enough and all developers should be familiar with its syntax in some level.
Many years ago I worked in a large enterprise and they always liked to add more and more layers. Instead of writing nice SQL queries, they used a framework named iBatis (still active:
https://blog.mybatis.org/). So as a developer you needed to understand both SQL and this new framework which had all kinds of quirks by itself.