Flare fittings need to be as straight as possible. There is a tendency to just push it over into alignment and get the b-nut started and then crank it down. This usually works but sometimes doesn't.
You definitely need item 12 completely loose when attaching the flares to the injectors. At this point with a leak you need to determine why the flare is not seating on the injector cone.
First remove the tube and the injector and get to some decent light.
Inspect the flare and the cone of the injector - Any piece of dirt between these surfaces could have embedded.
PS - Also remember there are two parts
to the flare fitting. The tube flare that seats against the injector cone and the nut flare that seats against the "outside" of the tube flare. Make sure the nut seats on the flare properly as well and there is nothing contaminating that joint surface.
Also inspect very carefully the shape of the flare - If assembled in misalignment and torqued down a permanent deformation of the flare could have occurred.
Also inspect the flare for a ridge or groove. Sometimes they can take a set especially if overtorqued at some point and now when reassembled they are seating against each other in a different location.
Sometimes you can lap the flare surface.
If this looks good proceed.
There are several "telltale" compounds available. Dykem blue which is like a blue ink. There are brands that are tape as well. Apply the telltale to the injector flare and carefully assemble (so as not to smear the telltale) on a bench or table "hand tight" - Remove and inspect the flare - the telltale will transfer to the flare and you may identify a high spot or low spot although with a leak this minor it may not show up.
They key point is to check for grooves and/or ridges on both surfaces (flare and cone) and then make sure the supporting clamps (item 12) are completely loose and you are not introducing any side stresses while aligning the flare with the cone.
Finally use a torque wrench and a flare fitting wrench. 90% of the time it will work out find but overtorquing is as bad as overtorquing as the flare can be permanently deformed.
PS - Don't forget there are two parts
to the flare fitting. The part that seats on the injector and the nut that seats on the "outside" of the flare. While on the bench check the nut is seating properly on the flare and that there is no contamination on this surface.