
That really isn’t how that works. The US has declared that they won’t allow the international courts to get involved, but that doesn’t necessarily prevent those courts from disagreeing.
“Jurisdiction” is only a thing when a court answers to some higher authority who has limited what that court can do. Since the international courts theoretically don’t answer to the US government, they can make any ruling they like.
They’re unlikely to bother, since they probably won’t be in a position to enforce any ruling against typical foot soldiers, but they absolutely could if it came to that point
It’s far harder to achieve mass manipulation of the ballot when it’s all being handled by a lot of human hands. If it’s managed by computers, then by finding a bug or other vulnerability in the software or database you could alter the whole election.
Meanwhile, to manipulate a paper ballot & hand-counted election in the same way you’d need the cooperation of a huge number of people, and you’d need them all to keep their mouths shut. That’s far more difficult than defeating a computerised system