I don’t think Wizards will print a multiplayer card in a 1 vs. 1 set. Voting doesn’t make sense if the outcome is determined by only one player. I could be wrong though but I feel like it is a bad design for a set that is designed to function like regular sets.
Also it has never been reprinted: (this is a response to your ‘Both of these cards have been printed recently enough and in enough sets’)
https://scryfall.com/search?as=grid&order=released&q=!“Council's Judgment”&unique=prints
You know what, I saw the Vintage Masters printing and for some reason thought it was in paper as well. Sorry for sharing misleading information. I think Judgment probably has a similar supply to
Toxic Deluge given that Conspiracy was printed quite a bit more than Eternal Masters, but I don't know how C13 figures into the equation.
I don't think
Council's Judgment being a multiplayer card actually disqualifies it from being in Modern Horizons. It's digital reprint for VMA was a 1v1 set. WOTC has actually put multiplayer matters cards in masters sets before. For example,
Deadly Designs, and
Prossh, Skyraider of Kher were both in A25. To be fair, neither of these cards mention voting, but neither card was meant for 1v1 play.
In addition, I believe that
Council's Judgment was designed and worded so that it would be playable in the eternal formats. The vote in 1v1 is supposed to only be determined by one player. It's a clunky work-around to targeting, but I don't think that makes it a bad design.
Since modern is the most widely played eternal format, I think
Council's Judgment would make since as a BaB promo, given it's proven playability in legacy. The voting wouldn't pollute limited, since it would only be the promo, so casuals wouldn't have to wrap their heads around it. It's also a good way to sell MH boxes to EDH players.
That said, your point about
Council's Judgment using voting is far from moot. Given WOTC's general apprehension to mention multiplayer magic outside casual/multiplayer sets, it is entirely possible that the voting dynamic is disqualifying for
Council's Judgment. However, I think the gameplay implications probably outweigh the clunkiness of it's wording. If this is something they want in modern, I see no reason why they would let the voting get in the way of that.