Ok, if I understand what you want, here is what I would do.

Click “Macro” on the toolbar and select “Edit/Create”
Copy and paste the following into the window.

# Set default icon for any waypoints that don't match your if statements.

$_Symbol = "Default"

If $d_Terrain = 2 and $d_Difficulty = 3

$_Symbol = "Airport"

EndIf

If $d_Terrain = 3 and $d_Difficulty = 2

$_Symbol = "Bank"

EndIf

I picked two icon names that I know exist in MapSource. Change them to whatever you want.

Save the macro. Give it a descriptive name and remember where you save it.

On the Mapsource export screen, check the box that says “Use Macro for symbol generation”.

Click the browse button and select the macro you just saved.

Set everything else the way you normally do and save.

I don’t have MapSource, so I haven’t tested this with MapSource, but it works with everything else I’ve tried it with. If this doesn’t work, I can think of a couple of different things to try.

Forgot to mention, but I’m sure you figured out that you can add whatever combinations of D/T you want to the macro. There’s also dozens of other variables you can use instead. I’ve been wanting to do the same thing with $d_HasCorrected to show solved puzzles differently, but just haven’t done it yet.