I see
So, to get this straight: All the three available buttons are set to a fixed ItemID and to a fixed behaviour. I suspect so because there are no hints what those buttons exactly do, so it must be hardcoded somehow.
Let's take the 25m-260m switchable depth gauge fo an example. What I assume is that in stock SH3 (and MFD also) the 260 version gets printed first and the 25 version afterwards. So the only dial you see in the game is the 25 version.
Then one button refers to the 25m dial and toggles it's visibility. So, when you click it the 25-dial gets invisible and you then see the 260-dial (and the according pointer+value).
Is this right ?
What I would do then is to throw the OLC dial bar overboard to get the switchable depth dials again and split all other dials of MFD up into single ones so that they don't need to be switched.
Also, I would leave out the engine telegraph completely because you can easily control the speed setting by hotkeys. All the other 5 dials are important, though.