The shape is square directly out of the hall sensor. The cutout on the crank (or dizzy rotor) dictates the primary composure of output. EZK or ignition module sharpens the shape via Schmitt trigger logic gate/s.
For your flow chart, may I suggest the Tacho be off a split to the side of the ignition stage?.......not through.
LH and tacho share a common tach input.
The flow depicted suggests the signal flows through the tacho (which could infer a possible point of failure) ??
I'm not really approaching this as a flow chart per se, but rather a "points of possible failure" approach. As indicated, there is a splice behind the tachometer that sends signal to both the gauge and the LH ECM. Maybe call out that splice and send one leg to the tach and the other to the ECM?