I could have answered you a few years ago when I played with modding P&S. Unfortunately, I don't remember.
Maybe, before looking at the Scripts files, you could try to modify the
squads file comparing it with what have already been done (ie. modded squads files), if you haven't done it yet :
1) Download, for example, Cronos' mod :
https://www.slitherine.com/forum/viewtopic.php?t=110276
2) Open squads.csv both in your Vanilla P&S folder (in your steamapps if you use Steam) and in Cronos' mod.
3) Also open squads.xlsx in your Vanilla P&S folder
4) Compare a type of artillery in both squads.csv files. For example :
In the mod :
Saxon_Heavy_Cannon1,142,Allies,1,Artillery,Artillery,1,60,25,200,20,36,0,1,6,400,1,0,saxon_h_artillery,100,0,1,0,0,0,-1,1,0,200,100,200,0,100,100,0,0,100,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,,0,0,0,100,,,-1,6900,1,-100,1,100,,,0
In P&S :
Red_Heavy_Guns,22,Axis,2,Artillery,Artillery,1,60,25,200,20,50,0,1,0,0,1,0,Heavy_Guns,100,0,1,0,0,0,0,0,0,0,0,0,-1,1,-2,0,0,0,0,0,0,200,100,200,0,100,100,0,0,0,0,0,100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,100,,,,
5) Look for numbers that are different in both lines
6) Look for what these numbers correspond in the squads.xlsx file to understand their use :
For example :
- in the squads.xlsx file above, column AH is 'bombard_shots'
- in P&S : -2
- in the mod : 100 (if I am not mistaken)
7) Make modifications, tests, tweak values...
The best for you about 'bombard_shots' may be -2 (as in Vanilla), 10, 50, 70, 100 (as in this mod), 200...
Hoping that it will help and that I don't say too much nonsense, it's been a long time since I didn't mod
Hoping you'll get your way !
PS : first verifiy any changes of columns between the squads.csv in P&S and in FoG2, comparing the column headers in their Vanilla squads.xlsx (in your steamapps ?) (btw for this reason, my example about the AH column might be wrong).