Google translate doesn't like it
"david day festival happy"
It seems to prefer
>Dydd Dewi sant hapus.
I always flip to and fro between languages and tweak it until flipping stops making uncommanded changes.
Basically some human input has gone into it and it translates useful
phrases. You have to force it to translate words one at a time by only asking one word at a time but, if you try to put together a phrase from single words which you've only just learned and swap language away and back, it does not return what you expect.