Further on this; as you’re unlikely to want to use the full range (30-284) in a given performance, you might want to scale the min,max values at the controller end. (Keysteps allow this via the Control Center* - shame you can’t set the Rate knob to send out a CC)
Even when you letterbox the incoming CC value, however, Midihub tempo will still only change in increments of 2; @Giedrius has hinted at scaled mappings for some time so my guess it that “fine scale” adjustments may come along with that.
-* also check MIDI Thru is on in MCC. Then you can plug another controller in via KS MIDI-input for more mappings!