Starting one year and 10 months before, I started to extend JEM with a responsive override.
Now, there are some good news for all of you using The Responsive JEM!
After working hours and hours, I were successful to include The Responsive JEM into the original JEM.
I don't know what kind of plugin want. Normally in the descriptions of event and venues, the plugins like you described should work.
the joomla custom fields are not integrated in JEM.Only the JEM custom fields.
PHP 7.2.9 on different sites
JEM 2.3.0dev 2.0M and specials with Joomla! 3.9.3 stable on livesites
ja_simply, ja_purity_iii, multilingual DE EN IT FR