My suggestions:
;------------------------------------------------------------------------------------------------------------------------------
; Enemy army composition
;
; These settings are used to control the composition of enemy troops, at the start of the game and later on in the campaign.
;------------------------------------------------------------------------------------------------------------------------------
; Percentage of troops that are actually placed on the map at the start of the game.
; 100 = All "default" troops are placed.
; 200 = Twice as many troops are placed.
INITIAL_GARRISON_PERCENTAGES_NOVICE = 100
INITIAL_GARRISON_PERCENTAGES_EXPERIENCED = 100
INITIAL_GARRISON_PERCENTAGES_EXPERT = 150
INITIAL_GARRISON_PERCENTAGES_INSANE = 200
Why not make INITIAL_GARRISON_PERCENTAGES_EXPERIENCED = 125 ?
; Percent of troops converted to extra elites in enemy groups
PERCENT_EXTRA_ELITES_EXPERIENCED = 0
PERCENT_EXTRA_ELITES_EXPERT = 25
PERCENT_EXTRA_ELITES_INSANE = 50
And this PERCENT_EXTRA_ELITES_EXPERIENCED = 10.