So I have this theory, it still translates, but the VisuMZ Option disabled the option to switch between languages, therefore you were stuck at the original language. Turning VisuMZ Option off enables the option again and now you can switch between languages and you can see it's translated.
If this is the case, the localization plugin doesn't have any issue, it's due to VisuMZ Option hiding the option for you to change languages. I can't make a compatible patch for VisuMZ Option because they obfuscated their code, but there's another way around this, which is to enable the plugin parameter Add Command To Title. Turn it to true, and players can change language via Scene Title instead. Tell me if it works.