You want to define which EQ frequency is being boosted the moment a note is received.
But, this I don’t understand - you want the EQ to gradually slide from the start towards the end value over some amount of time?
Or does the start/end simply refer to a given region of the keyboard that have these special EQ treatments ?
In any case, one possible approach would be to use the LFO as a custom “lookup device”. This approach has been used for tuning all sorts of native effects:https://forum.renoise.com/t/doofers-tuned-devices-bundle/41764