The best way to calibrate the AI on the Unipi 1.1 is to turn off the transformation for the AI, connect a voltage source with an output of exactly 10 VDC and look at the value on the AI in the Mervis IDE. Remember this value and then insert it as parameter X2 in the two-point linear transformation.
Set parameter Y2 to 10 if you want to get the voltage value directly, or set to 100 if you want to get the percentage value [%].
Set both parameters X1 and Y1 to 0.
In the attached picture you can be inspired by the settings for my Unipi 1.1.
Have a nice day