I guarantee you if issues exist, it's because the core developers are not using the i18n support. They probably haven't needed to. I've made over a dozen Ubercart sites and haven't needed this yet either.
You'll need to find a developer to take up your cause, or hire one so that they do. This is really the only way to get your issues fixed in a reasonable amount of time. Bribes do go far.
With that said, I get angry when issues are brought up and not integrated back into core, there seems to be a lot of multi-language issues going on here.
Maybe you could write up a full review of patches that need to get integrated, now that you have the eyes/ears of developers.