Congratulations on the new specification and work.

Ciro Santilli has built upon something I had started for a Markdown Test Suite. It is a very good work on a comprehensive Test Suite, with a test driver. You can see the test resultsfor something around 16 implementations.

It seems not wise to duplicate the efforts. I'm wondering if we should stop our own effort on this project.

Opinions. What would be the best way forward?

I suggest examining the spec and combining any missing tests -- tests you created that have no counterpart in the spec -- as pull requests. That would be great!