Earlier quoted context omitted.
That exists. This blog post explains how to add Welsh names: http://cardiff.theodi.org/2018/02/23/mapio-eich-milltir-sgwa...
There's quite some resistance to adding translations and transcriptions, as they aren't really names as such. An example would be small towns in the US. They probably don't have a Welsh name, even if there happens to be a direct translation into Welsh.
We get silly things in Wales like Cymraeg mono-lingual government announcements/adverts on the radio (accessible to about 7% [1] of the population vs c.100% if they were in English), motorway signs that are only in Cwmraeg for half the people passing them (they change over, useless if you passed already), travel announcements in Cymraeg first. Heck, if you ring 999 in an emergency you have to wait for the Cymraeg speaker to finish their 20s message before you start your call.
Welsh people use British-English language predominantly; the Welsh name is the name in English, the Cymraeg name sometimes differs.
[1] roughly: ~15% of the adult population say they know any Cymraeg, half of those are fluent (self reported). FWIW half of those fluent say they prefer to use English. So one could argue you're catering to <4% of the population.