I don't even know if they were technically illegal. I would imagine that the courts would have to weigh in on this. Seems like fairly uncharted territory.
Buying an ad as an individual or boosting a post on Social Media is against the law? And the intent seems rather scattershot; like social media marketers trying to make a few bucks.
And I do understand the foreign national part, but it still seems shaky to me. Especially given that China and other countries drop serious coin on our pols and electoral system.
Laws are for little people. BIG "people" have a different track of justice.