I found a minor cosmetic issue with the SpellChecker plugin that bugged me somewhat, so I made the status bar menu and settings combo box use human-readable language names (i.e., "English (United States)") rather than the abbreviation which is not always clear to the user (i.e., "en_US").
The changes are in the attached patch. You'll notice a very primitive implementation of GetLanguageName(), but I ended up doing it this way, because I couldn't get it to work with neither wxHashMap nor std::map<> for some reason. I did lose patience, but still hope someone else takes the patch and refactors it to a more efficient alternative. For now, you can already get proper language names listed in the user interface using this patch.
EDIT: Fixed a bug in the previously uploaded patch.