https://openstreetmap.org/copyright | https://openstreetmap.org |
Copyright OpenStreetMap and contributors, under an open license |
https://openstreetmap.org/copyright | https://openstreetmap.org |
Copyright OpenStreetMap and contributors, under an open license |
The multiple values in alt_name look to be variations in orthography and therefore perfectly valid information (see Wikipedia re signs for the village https://en.wikipedia.org/wiki/Trellech). Given that there is a name:cy tag, the names can be taken to be the english forms. This area has been english-speaking for centuries.
AFAIK name tag is supposed to hold single name - see https://wiki.openstreetmap.org/wiki/Key:name
And if multiple values exist add them separated by semi-colons.
The wiki often fails to cover the full complexity of the real world.