I've used the plugin CodeStyling Localization to translate commentpress core into french.
The translation went OK (I'd be glad to give the files to anyone who'd like it, BTW) but my site won't use the plugin po/mo files, even though they are properly named and placed. Strangely, the template po/mo files (created by and translated thanks to CodeStyling Localization) seems to work fine.
I'm a writer, not a developer, so my knowledge won't go as far as that ;)
The site is http://apolog.noenaute.fr and I can make you an admin-user account, if you need one.
The site will display my third open-source / public domain novel, and I really look forward to use comment press to experiment another way of sharing with my readers.