Technical quality test teams largely do not have the capability to understand any foreign language other than English.
But really, do you need to know foreign languages to perform Internationalization testing?
Here are a few points that would help you make a decision –
Firstly, you would be testing an English product in a localized environment and not the translated product. For example, an English application running in a German environment (OS, etc).
Test cases to perform step-by-step testing are available and help in navigating the application in a localized environment even if you are not cognizant of the complete functionality of the product, or if messages are being displayed in a foreign language. All the supporting applications would be in the localized language but your application would still be in English. Which means, all the error messages, popup messages, and so on will continue to remain in English.
You may have to navigate the localized environment, for example, configuration changes in the OS etc, and the technique to do this is to look for similar icons/symbols/pages and so on, in the localized OS as you would do in English OS otherwise. If you are having difficulty with language-specific messages which you cannot understand, then you must use the assistance of an in-house localization team or translation agency, which I assume you will have in your organization.
It time to reinvent your testing strategy and introduce I18N testing right from the planning phase.