Lol we don't have that many people (especially kids) with welshy names in wales. Most have regular names like Katie, Emma, Sam and Andrew.
That said, I did know someone called Ieaun once and a girl called Rhianydd (where double d is pronounced 'th'). They would be quite a task in katakana!
Probably easier to call those exceptions ジョーンズさん！ Jones is the most common surname in wales, I'd say about a quarter of the people I know have that surname!
