Funny this came up, I spent most of my day mixing a few yards of block fill yesterday from scratch. I fully understand that you want buy it in bags for a small quantity like that. I would NOT use Type S mortar, even if the code allows it, because no lime should ever come in contact with rebar, and it will never be strong enough to hold the Titan anchors that are called out on your plan.
I would look into trying to find Spec Mix grout if you're hitting a dead end with Quikrete. They're the same company, Spec Mix is the professional side.
Core Fill Masonry Grout | SPEC MIX
www.specmix.com
I've never seen a fully grouted foundation called out on a blueprint here, and have no idea what filling cells without rebar below grade would accomplish, so you don't need as much material, likely. Also, notice when looking at the specs for the grout mixes, the "slump" is listed extremely high, like 8-11", which is as wet as you can get when it comes to cements, concretes. I would pour all of the vertical cores wet, then mist the bond beam so it's not dry, and pour the bond beam slightly stiffer so that it has more strength to hold the Titan screw threads from stripping out. Be sure to consolidate the bond beam grout well.
