The script works well (sometimes need to retry, but no issues there). The documentation could be a little bit clearer:
It says “Copy the performers in recording Advanced Relationships to the selected recordings “artist” field”
(a) clarify that it will copy all performance artists in the recording-artist relationship and (b) say what happens re as-credited names. (Not sure what “Advanced” relationships are).
In terms of improvements, maybe the ability to not copy all performers (i.e. certain types only).
Plus it would be nice if it worked on the edit->recordings page (which is where I was expecting to see it).
All in all, nice-to-haves - the script is great as it is.