Are translations valuable to Phd admission committees?
Unless you're in the humanities, where the ability to translate source materials may be a critical need, what you're doing would be considered an example of a "service activity." You can certainly list such an activity on your CV and applications, but its impact on an admissions committee decision will be minuscule. You're much better off, as your advisors suggested, producing original research results.

Moreover, if you're planning to study in an English-speaking country, you will want to spend time improving your written and oral communication skills, rather than translating materials into your native tongue.