My production site is www.mwphrf.org, but to isolate this issue I have built the temporary site shown above.
I am receiving an error message whenever a page is assigned to the JA-edenite-II template style is invoked with the compatibility plugin disabled.
The site is a simple test site with virtually nothing installed besides the base Joomla (version 5.4).
I have installed the JA-edenite-ii template (v2.1.0), JA-acm (v2.4.2), the T3 system plugin (v3.2.2), JA extension manager (v2.7.6) and JA-login (v2.9.0).
When I set the JA-edenite-ii template style as the default for all pages (just the home page), it works fine with the compatibility plugin (v5.0.0) enabled. But when I disable that plugin I get the following error message:
Class "Joomla\Component\content\Site\Helper\RouteHelper" not found
In order to move future releases, I'd like to turn this compatibility plugin off. With Joomla 5.4 there's another compatibility plugin (v5.4.0), but I have not played with that one yet.
Unfortunately, the is no debugging information that I can find that helps identify the root cause of this error.