I am guessing its an electrical converter you fitted, right?
I asked this question of a seller of the electrical converters before as I read elsewhere that sometimes the ecu needs to see a speed readout in order to work right, so you need to fit 2 converters. I didnt get an answer as I guess the Caldina information is scarce. It depends on wether the ecu takes its speed reading form the clock or from the gearbox, and I dont think many people know what it does as the ecu is ST215 specific and it controls the box.
When you say changes are late, do you mean all the time in all gears? The auto box has a function that when its cold, the car stays in 3rd until the temp gets up a bit, but once its warmed up it chnges through all gears.
Easiest way to do it is to covert the dial to mph. I did it by photoshop and printed it onto acetate, then replace the original dial.