I dont know the markup to quote, and Im too lazy to learn, so:
"My fear with this would be that the di-Gymraeg, born and bred in Wales may find it difficult to swallow if a Welsh language event were to become very commercial."
This is true, but you imagined skipping a step. The commercial appropriation would not be of the language. It would be of being Welsh in general - a persona. Of that, a few true-meaning culturally identifying people could find a pathway to the language.
Of the population of people learning Irish in the States, many started off as general Celtofiles. Not necessarily of Celtic genetic descent. The desire to delve into Celtic culture is very strong here. And Irish, rather than other Celts get the bulk of the language bennefits. Possibly because everybody knows an Irish cultural stereotype, right? Talk like a leperchan, drink whiskey, pick clovers, and ... I can't go on... it's too denigrating. But it has a weird effect of instilling pride, even if it's also debasing.
I'm not suggesting the wholesale marketing of perjorative Welsh stereotypes, but one single tradtion that people can love and grab ahold of. Like wedding spoons - something that may not exist in actualy practice. Or whatever - my knowledge is very weak, so I won't risk saying something silly, like hill walking.
By fostering a general love of culture, the specific may grow as a sub-population. So I'm sorry if I sounded like I was suggesting a language immersion beer garden full of dolts. I guess the question I'm posing is twofold. Do Welsh speakers want to speak the language with non-natives? I think all languages should have that as a goal in the long run. And what does Wales have that no one else does? In the UK, that might be something as unlikely as surfing around Bristol and Cardiff which I'm told is a thing. Finding the persona, sell the persona, cull the interested from the beer garden, promote the language. Which may sound a bit like growing a tree of oranges to find a lemon, but I've seen it work in practice.
And it's also the antithesis of another idea I support, fostering language at home.