Portuguese (Brazil, pt-BR) created, tested and released.
While testing, when using the en-US locale there was an error displayed on the lower part of Firefox window:
This didn't happen with the pt-BR and an other (es-ES) locale, neither with en-US locale before adding the pt-BR one to the package. I've reviewed the files on root of xpi (chrome.manifest, install.js, install.rdf) but couldn't find any problems, and these were the only ones altered outside the locale folder.
Edit: now it began happening on my locale too, after trying to translate the menu item displayed text... working it out...
Edit: reverted the changes and now it works again. There might be something to do with special characters in the menu item text, but I don't understand why the en-US would stop working if it wasn't altered, and it has no special characters there. Hope mikeshk has better luck adding the locale...
But I liked this extension anyway!