We will look at this.
I assume you are using midi to control it with the keyboard?
Have you tried using automations ?
Because as the MIDI precision is under 128 it can not be really precise. except if you use 14 bit MIDI.
A workaround in that case might be to use 14 bit MIDI and map it in your host to the tempo parameter directly.
To be sure, first try in your DAW to change the parameter directly (not with MIDI but with the DAW GUI, or in Analog Laboratory's GUI).