Need a script which uses the Rosetta internal XML parser to check upstream Mozilla translations

Rationale:
Currently when uploading Mozilla translations into Rosetta, certain languages fail to import, because of syntax or format bugs in the .dtd or .manifest files included in the XPI tarball. These bugs do not get detected by upstream developers/translators, since Firefox is more tolerant, while Rosetta's XPI parser bails out.
I currently fix those issues manually, rebuild the XPI tarballs and upload them again to Rosetta until they get accepted. This sometimes needs multiple attempts, since there are often multiple bugs in the XPI tarballs and the XML parser bails out at the first one it finds.
What's more, those bugs, even when sent with patches to upstream, don't get fixed in the actual stable release which we are importing in Rosetta, but with chance in the current development tree. However, since the directory structure in the XPI tarballs and the upstream Mercurial VCS don't match, the patches I generate against the XPI tarballs are pretty useless for upstream translators.
Therefor I'd like to be able to check all .dtd and .manifest files in the upstream VCS with the Launchpad XML parser to be able to fix those issues before the translations get released in the next stable release.

Since Launchpad wants to import upstream sources, I think this script would be a very useful asset, too.