Here's an example of how to hunt down the reason for some bizarre results and rectify it.

The screen shot shows what is roughly the values for the elevons of my Grumania Eurofighter, in elevator mode. They have a lot of up travel but not much down travel. (In aileron mode they have very little travel at all) As you can see from the first diagram, the position of the servo arm is bizarre. Can you see what is wrong in the values to cause that? I have put in my default servo travel of 40 degrees either side of centre, and the required elevon travel of 40 degrees up and 15 degrees down. That's the clue to the strange result, if the servo rotates the same amount both ways, how can it make the up elevator more than twice as much as the down elevator? It has to use a huge amount of differential, this can happen at either servo or control but the program is constrained to only adjust the servo, because I have defined the control horn offset in box Xc. And that is why the servo arm has been rotated so far round. In reality we would position the servo arm at right angles to the pushrod, and in the Tx we would turn down the travel % for the down elevator to give less travel. So that is what we have to tell the spreadsheet. In the second screenshot, in the Rc- box I have turned down the servo rotation to 15 degrees (as I would by turning down the travel value in the Tx from 100% to something like 38%). Now the diagram looks normal again, as the servo arm no longer needs to have a huge offset angle to provide the necessary differential.