“Wa-la” is all too common these days. Anyone under 30 in America would probably use it rather than “voila.”
“Wala” is a misspelling and mispronunciation of the French word “voilà’.” Common or not, it is incorrect and meaningless as spelled and mis-pronounced, no matter who in America is using it. I don’t know anyone of any age-including kids in HS-who don’t know the correct word “voila” and what it means-and I live in a rural area where most kids are home schooled or go to the small private school here. If I can’t spell a word or don’t know what it means, I don’t use it...
And yes-I’m an unapologetic grammar Nazi...