I normally add in some rarer castes that are better at combat than the rest like NORMAL_GOBLIN, ELITE_GOBLIN, and HERO_GOBLIN then I adjust POP_RATIOs of these castes so I get a percentage I like (heros are 15%, elites are 30% and normal goblins are 55%) then each ambush/seige is always a random mix of all goblin types Hero goblins being close to legendary (rank 10 in combat) with interactions to "boost" the stats of nearby goblins, so when leads the command of a squad it makes that regular rabble into not so regular rabble.
Also another thing to do is to tweak weapon attack settings, Axes at the moment (of vanilla) are 800cm3 with a contact area of 40,000% (which is 400 times it's area) which is 320,000cm3 of area to cover. with a 6,000% (60 times) penetration factor which idk the math for penetration because material properties also take effect here. And also whatever force is used to do the attack (Strength and size? of creature) multiply that by 1.25 (25% more)
Compared to a Short Sword which is 300cm3 with a contact area of 20,000 (200 times) lets it cover only 60,000cm3 with a penetration boost of 4,000% (40 times) since it's got a lower contact the penetration boost doesn't need to be so high (more area to contact, the more the weapon can be resisted)
Also the fact that a Warhammer is smaller with a more targeted contact area of 10% makes them better than maces which are twice the size (400cm3 compared to the mace of 800cm3 and contact area of 20%) makes warhammers much better as blunt weapons and lighter than a mace (since they are smaller and thus weigh less, they still have a spear like attack)
Weapon stats are all over, and not very balanced. Leaving the fact that Bows the better ranged weapons (lighter but same shoot force/vel) War Hammers the best Blunt, and Axes the Best Edged (for cutting, best staby edged is spears) so really if possible outfitting your army with just War Hammers, Spears, Axes, and Bows would have you with the best weapons
if anything attack prepares and recovers and even some Velocity boosts, contact, and sizes need to be adjusted to better fit the weapons so that using a short sword would allow for faster and more attacks, at the cost of being not that good at cutting parts off, but good for cutting down to the bone. But having the axe be a bit slower but more fatal if it lands.