You can tell it's _not_ Cymraeg because of the "j"s.
Despite Jones being the stereotypical name for people in Wales, the old Welsh language, Cymraeg, doesn't have a J, nor have Z, K, V, X (IIRC). Jones is an English loanword, brought over apparently with the Norman conquest (though derived from Hebrew).
The modern language of Wales is of course British English with a ~100% use rate; Cymraeg still has an approx 8% (but falling) of the population who say when surveyed that they can speak it fluently, however.
Off-topic, but I think that traditionally, the longest official word in German was "Rindfleischetikettierungsüberwachungsaufgabenübertragungsgesetz", the name for a law about testing and labeling of beef, now repealed. This word (63 letters) was of course not in everyday use by most people, but it was actually in the law.
At the risk of losing more karma... isn't the domain registered to stop this gwea.com itself?
The hacker, though, didn’t register the gwea.com domain name. On Friday morning, a 22-year-old UK security researcher known online as MalwareTech noticed the address in WannaCry’s code and found that it was still available. “I saw it wasn’t registered and thought, ‘I think I’ll have that,’” he says. He purchased it at NameCheap.com for $10.69, and [...] [1]
If it is, it seems to contradict the whois record.