Hi De Tran,
You can contact the Gramps Developers on the mailing List
I have listed your translation on the following Page
More information on translations can be found on this wiki
I personally thank you for helping to improve Gramps
Submitting updated translation file
Hello, Thanks for your updated translation.
Which branch/version of Gramps is it for as opening the file shows "Project-Id-Version: GRAMPS VIETNAMESE 3.3.1-1 - V 1.0\n" is that right? If so that's very old and the next released version of Gramps is 5.0.
For any future updates please submit it either as an attachment on Gramps bug report or directly to Gramps Github for the appropriate Branch/version of Gramps. Please do not upload the translation file to the wiki as no one will see it!