When you enter a fan speed in the "Fan speed" box, it is limited to 100%. So I'm guessing you are double-clicking on the setpoint text in the left-side list to edit it. You can enter anything you want there. You could even enter "abc" if you wanted, but obviously, you still want to stay within 0-100%.
It doesn't matter what firmware or printer you have. You always enter a percentage from 0-100%. Basically, if the "fan speed" input doesn't allow the value you want to type into the list, then you shouldn't be putting it there.
If things such as "Support Infill Percentage" only let you put in values of 0-100, then shouldn't other things that are 0-100 percentages work the same way?
I can't put "abc" into "Outline Overlap" because it is a percentage, but I can put it into Fan Speed which is also a percentage?