It sounds as EL's event view doesn't trigger content plugins - or the way or names had changed since Joomla 1.5.
You could take a look into EL's event view code (view.html.php) and search for "trigger". There should be something like "$dispatcher->trigger('onContentPrepare', ...". Then you could check on which events ("on..." functions) PhocaMaps plugin reacts. Maybe the names have changed (e.g. onContentPrepare vs. onPrepareContent).
If so you can adapt EL's view code and enhance PhocaMaps by supporting both variants (by adding new function with the other name which simply calls the corresponding function, maybe adapting the parameters if different).
used very long time the eventlist 1.02 for Joomla 2.5. And I thought it's nearly stable.
Then I helped getting the JEM 2.0, and I've seen, there were a lot of problems behind the facade, I've never seen.
For that I propose you to try the new JEM 2 for Joomla 2.5. As much as I know you can use it neneath the eventlist.
It has a lot of added useful features which never were in the old eventlist 1.0.2. And the developers like Hoffi made good work to make it safer.
on JEM 2.3.0 stable in latest Joomla (3.9.22) Protostar php7.4.5
btw: JEM is based on EL and you can import data from EL into JEM. But it's also a completely different extension so you can have both JEM and EL side by side on the same site without any interferences.
Also JEM triggers in new style - but there you don't need PhocaMaps because JEM has integrated map support.