one of my colleagues asked some months ago to add the eu_ES language to https://www.transifex.com/open-edx/open-edx-releases/languages/ but he hasn’t received any answer yet. I can see that there are two requests (eu and eu_ES) without any answer:
Please, who is in charge of accepting new translation languages in Transifex for Open edX? Could he/she accept the eu_ES language? and if not, how can we proceed in order to be accepted?