It was suggested that translating dates, numerical values, prices, email addresses, etc. doesn't make much sense.
I would say that it entirely depends on what's the pertinent purpose of an attribute, and it has to be carefully decided during the planning stage. There seems neither a technical, nor any other reason why dates, numerical values or other types should not change with language context. An attribute with translatable or untranslatable e-mail address simply stands two different attributes, and both can have their specific uses.