There is already something like that for the CPANTS/kwalitee site, it has a test that checks whether there is a changelog present in the distribution: Module::CPANTS::Analyse::Kwalitee::Files.

Aside from that: What would be the benefit to test whether the changes file has a special syntax? The module would have to handle multiple styles of changes files I guess, as there is are lots of variations of 'Changes' files out there. Some even name them 'HISTORY' or 'WhatsNew' or what not...

At least I wouldn't find such a test that useful, as I'm not that picky about the format of a changelog. As long as the most important changes are documented somewhere and somehow. So I guess the most important thing is, that the Changes file is present.

But such a test would of course only benefit the maintainer/author of a module, and shouldn't be in the distribution IMO.

That is of course just my two cents, if YOU find such a module useful and would use it, then I don't see any argument against such a module.