The IFR controls solid fuel. It's the main determinant
IAB is a correction on the IFR, and if not too much is added, the air injected lowers the density. If too much is put in it stalls the flow or the air bubbles coalesce and it produces inconsistant spurts of air and fuel bubbles.
The TSR is a variable air bleed acting on the lower density mix of air and fuel.
The TSR is a variable fuel restriction on the lower density mix of air and fuel.
When the pressure difference on the IFR is high enough, flow is choked. More pressure will not flow more fuel. This is part of why the idle system leans out (on a stock engine) as thottle opens from idle. On a hot rod with low vacuum at idle, its will increase fuel flow with increasing manifold vacuum before choking.
If the idle chokes fuel too early relative to the mains starting, then the IFR needs to be made bigger. and vica versa.
The same AFR can be achieved with different IAB/IFR combos, but the larger IFR will carry the idle system's contribution further into the mains starting.