Here's my thoughts so far....

The throttle slowdown serves to keep the signal to the throttle servo synchronized with the servo position. It prevents the signal from changing faster than the servo can move. I think it would need to be equal to the servo sweep time provided by the servo manufacturer.

The mixture gets slaved to the throttle channel output. This synchronizes the mixture to the throttle position and separates the fuel needed for acceleration from the fuel needed for a steady state operation at a given rpm.

We add fuel to that base mixture fuel amount and we do it based on throttle speed and only on increasing throttle. How much to add is a guess at this point but a single additional channel could be used to define the acceleration fuel amount as well as reading the throttle position.

I'm just spitballing at this point but it seems doable and it sounds like it would be more easily tuned.