As someone who has suffered with log4j and it's "successors" over the years, you're not convincing me.
I'm still missing some precision here. What does this mean?
add the missing functionality to the existing class
Do you mean the JS console object that is currently visible to most every web browsing widget available? Or do you mean the "Debug Console" Cordova plugin?
I'm reading what you're saying is that you want to standardize the additional methods/properties that the iOS version has added to the JS console object, across all the platforms. In which case ...
If we have to add a new class every time something is missing, we will start a path that has more and more plugins and source files. This is not a good way forward either, since constantly adding classes will add complexity and more than one way of doing each thing.
Here's my suggestion, based on guesses on your use case.
We create a new logger property on cordova. The primary use for this is plugin code, not "user land" code. cordova.logger will have whatever minimal logging level stuff we need. We'll rename the "Debug Console" plugin to "Logger", or whatever.
For platforms that do not have a console object visible in user-land JS, or the one that's provided is sub-par or non-operational (iOS), provide an implementation of the FireBug Console API implemented with the new cordova.logger object.