Hi! You can sign up to be a volunteer translator at https://www.khanacademy.org/contribute (click the "apply to translate" button). 

Miss Charrow, can you help me join the translation project on crowdin? I have sent my application on crowdin but it hasn't fed back.

Hi Linh! What language are you interested in translating? Did you complete the application at https://khanacademy.wufoo.com/forms/khan-academy-translator-application/ ?

Yes, I did. Beside, right after I comleted my application on Khan Academy, they sent me an email, which told me to join a translate group on Crowdin. I would like to translate Vietnamese, but when I applied for translator on Crowding, I have been waiting to be accepted. If some kind of error made the managers can't receve my application, miss?

Dear Linh, 

If you do not hear back soon, please feel free to contact the Vietnamese language advocates directly - their info is available at https://support.khanacademy.org/hc/en-us/articles/226322087-Contact-Language-Advocates

Hope that helps!

Thanks!