I also encounter issues configuring the script and regex linter.
However, I use regex101 to test my regex, so I know that works.
If I remove the || true exit code workaround, I see that the right commands are issued, with the right stdout, so that works as well.

I see you already found an existing issue, sorry for the noise.

We don't keep this install at HEAD at all times

I understand, I didn't think this was the case anyway. I just figured I'd let this issue be known so it will at least be fixed.

We personally are not on any version with the new layout, so I can't say it fixes it.
I just drive-by reported a bug I saw on this instance.

One idea, to really spark the importance of getting to the root problem.
Adjust the language where necessary of course.