A player sacrifices Horizon Spellbomb, resolves the “search” ability, then pays G and draws.

How would you handle this under the current policies?

Had a brain fart on that one - deleted the offending post.

If the cards were drawn as part of the legal resolution of an illegally played instruction, due to a Communication Policy Violation, or were as the result of resolving objects on the stack or multiple-instruction effects in an incorrect order, a backup may be considered or the game state left as-is.

I think the ipg suitably covers this

Yes
Gareth quoted the relevant part of the ipg. This has been tweaked a bit during the origins update. It previously did not apply, it does now.

Horizon Spellbomb was always a challenge, when it came to wording policy such that we'd get to the desired result. Given the current wording, however, it's a fair bit better. As Gareth said, consider a backup, or leave things as is; no further remedy; record the Warning.

d:^D

Practically, what would you do? Infraction, fix, penalty? (ok, infraction is DEC)

From a practical perspective, I'd almost certainly record the warning and then leave things as-is. A backup here involves shuffling a random card from the players hand into the deck and replacing it with another one. The odds that the incorrect ordering of abilities impacted the draw are far lower than the odds that our fix will shuffle a pre-existing card from the players hand into the deck.