The answers are actually in this post thread
but you have to know basic BFME2 coding , and maybe scripting if needed
once you set up a functional -MOD folder , you test that it is functional by giving Aragorn some new health or lower build cost
A -MOD folder is a folder that contains all the necessary contents to allow for changes
usually INI.big , once extracted using Finalbig program is sufficient for beginners
or try creating a Map , and saving it , and playing it in game
by this I mean extract an existing map from Maps.ini and adjusting something like a tree , and see if your new map is read in game , once you save it correctly
-MOD folder makes this coding very easy , it’s the beginners steps
1. Adjusting the frequency of the catapults etc , in skirmishaidata.ini
2. Deleting the command button line , in commandsets.ini
3. Scripting the individual map , to disallow that catapult specifically for ALL players
all of the above will work , and give you any desired outcome
1.Adjusting the frequency will get it to 0% , never built , or other percentage for lesser build frequency
2. Deleting the button totally removes the item and no-one will build it
3. Scripting also will have no one build it , but can be on a set timer , so that a script to allow building the unit activates after a set time ( like 1 hour etc )
but basic mod setup , or map creating should be your first goal
then searching the file(s) in Windows for the word catapult , will show you many things
and playing with scripts , by opening a blank map in WorldBuilder , the program that is stored in the same directory as the main game
allows for map creating and script testing