I notice that JMOL chemical rendering filter hasn't been updated for 5 years, and the fork chemrender for 4 years.
Are anyone using these or anything similar?
Just to mention that just because the plugins were not updated, does not mean they do not work.
The Text filters API hasn't been touched for years and even if it was, Moodle has been always quite conservative in core API changes and there is a strong focus on backward compatibility.