You're welcome to use JEM.
The question is: Do you need old or archived events you posted in the old extension? Normally no!
If yes (because they are actual), you have to find a way to export this and to bring it into a csv which is compatible to the JEM. To find how is build JEM csv file, you can export a JEM file and analyse it.
Because it seems redevent doesn't continue, it doesn't need a plugin!
on JEM 2.3.3 stable in latest Joomla (3.10.2) Protostar php7.4.15
Personally I use t4_B5 template with t4_system plugin framework with bootstrap 5 and fontawesome)
(I prefer free "Signal" or paid "Threema" instead of "Whatsapp".)
Youre absolutely right - if they stop, no sense in programming a plugin, maybe only for my migration time...
I have a lot of People coming from Google for elapsed events, I have to take care for that. And we are giving seminars which repeat every year, so I have to recycle events often.
Markus
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Hilshof
Lebens- und Veranstaltungsraum
Sacha Sohn & Markus Welters
Winternam 132
D-47647 Kerken / Niederrhein