Ok, sorry, I may have misread your issue. Are you saying that the German CWA no longer works after an update unless /e/ updates their version of microG?
My old answer was about general support for the contact tracing framework which is a separate install on /e/. 
It’s already there, see Guide on how to use the Covid 19 tracking framework on /e/OS
Or jump right to the docs at https://doc.e.foundation/how-tos/microg-exposure-notification-version-implementation