I don't think exotic beetles are legal, period, no matter how they got here, with the exception of certain carnivorous species and such, (plus exotic stags are apparently legal to own in CA?).
EDIT: Whoops thought you were talking about like bringing them over yourself on an airplane lol, my bad!
If the beetles themselves flew to the US then yeah it'd be legal to keep them, but unless those species live VERY close to the border, it's highly unlikely that'll ever happen. Though some people might fake it and SAY they found them in the US near the border, so they can keep and sell them "legally"... I've heard of people doing the same with certain Mexican tarantulas, saying they found them in the US to avoid suspicion of them brownboxing them in, when the species in question have never been and likely never will be found in the wild in the US...