Sorry, I only started learning Python a couple of weeks ago.  Didn't
know that there was a ConfigParser module.  So this would really be a
feature request of ConfigParser?

Interesting you should mention Postel's Law.  Being liberal about what
you accept from others doesn't mean ignoring non-conformance.  Jon
Postel was clear that although you endeavour to continue when
encountering non-conformance you should always report it, lest
non-conformance propogates (sic).

I can think of two ways ConfigParser could report these problems. 
Either you give it a callback function it can call as it encounters
problems, or, after you have parsed a file you can call another function
that gives a list of any problems encountered.

If ConfigParser had this functionality it would then be straightforward
for the logging.config.fileConfig module to send these warnings to the
root logger.