Is it less discoverable than the proposed alternative though?

In both cases one looks up the documentation, in one I find that search for the line start requires a regex with "^" and in the other I find something like "begin with" of Simple Regex Language (SRL). I still need to read (or test) to find what "begin with" means and I still couldn't guess it - why not "start with", "open with", "first character", or a myriad of other possible options.

Whatever suits the user I suppose.

Since code is read more than it is written, how well do you think a colleague without previous knowledge of regexs could understand '^' vs 'start of line'?