If they could get people to install a mobile UI app that fetches instructions on what to up/down-vote, what to flag/vouch then they could and unlikely anyone would notice.
It is unlikely that enough people would check their up/down vote history, vouch and flag history and even then some would assume they fat-fingered such things.
Such a UI could also save and upload username and password to another site. Some people use the same creds on multiple sites.
I think a larger question to ask is if could they also be manipulating the people themselves who are reading these message boards prior to this post which later impacts such message board's voting.
Lol. If Israel could manipulate HN do you think so many anti-Israel posts would appear on the front page, and each mitigating or nuanced comment about Israel would be flagged so quickly? No, Israel does not control or manipulate HN.
Practically everything of political attention gets flagged, even if it is tech related.
There may well be a pro-Israel brigade going out of their way to move that along, but there is an equally rapid anti-Israel brigade. Nothing remains on the front page for long.
Not a single pro-Israel article, nor even any article that even mentions Israel neutrally, has ever reached the front page of HN in the entire history of HN.
So, no. Israel is not "winning the up- and downvote war" of HN.
It is unlikely that enough people would check their up/down vote history, vouch and flag history and even then some would assume they fat-fingered such things.
Such a UI could also save and upload username and password to another site. Some people use the same creds on multiple sites.