Based on the new planet locations it seems clear that the Horizon border or effectively border the Honiani, and are at most a subsector removed from also bordering the Ked Paddah. This is with placing the planets on the corward side of the specified subsectors when in doubt and with drawing the fuzzy borders just barely larger than strictly necessary to encompass all those major colonies, and without any knowledge of minor colonies/mining colonies they might also have inside their borders (compare with how much claimed space was assumed for Cardassian mining colonies when we got locations for them after Ghosts and Whispers).
Where exactly is the HBZ going to be? It seems effectively impossible for it to include a claim on a buffer zone between the Honiani and the Horizon without that being taken effectively as a declaration of war (imagine China was constructing artificial islands just a couple of miles off the coast of California and trying to claim those as new territory including territorial waters around them). A buffer zone between Ked Paddah and Horizon is perhaps a bit less of a stretch, but still seems rather aggressive. It seems what would make the most sense would be for the HBZ to be formed from unclaimed space between the Honiani and Ked Paddah (around the Tauni who would probably very much appreciate it), as well as a bit of the recently claimed space of the Rigel sector. Perhaps something like this?