Twitter is the only platform that I use that does not offer Welsh as a base-interface language. (FaceBook and WordPress both have, albeit imperfectly, support for Cymraeg).
Now, despite pro bono efforts of volunteers for several years — begun in 2012! — Twitter is quietly suggesting that Welsh, and other languages in development, will never be implemented on their increasingly text bloated service. (Nazis still have free run of the places, however).