Maybe try this in the raws , creature_standard.txt
Find [CREATURE:GOBLIN]
And under it add
[CRAZED]
[NOFEAR]
the 1st token should make them "specist"
Creature is 'berserk' and will attack all other creatures, except members of its own species that ALSO have the CRAZED tag.
Meaning goblins will hate and want to attack every non-goblins (as all goblins will have the CRAZED token) whatever the civ
the nofear should be helpful to get rid of various morale broken problems leading to overpassive enemies with current DF
Now by default, goblins populations don't mind going to live in a dwarf civilization or a human civilization, and with the current lack of way to know who is belonging to which civ, this is a huge problem, as you can't know who is an overpassive enemy and who is an overpassive friend.
And with the [CRAZED] tag it would be rather bloody to visit human or dwarf location, as goblins should attack non-goblins in those , even if they're on same civ
To get rid of that problem (if you see this as a problem, as in the opposite it could make things more .. lively or deadly), a simple method is to prevent goblin populations to go live in dwarf or human civs.
To do so, still in the raws, open entity_default.txt and find
[ENTITY:EVIL]
[CREATURE:GOBLIN]
scroll down until you see
[DEFAULT_SITE_TYPE:DARK_FORTRESS]
[LIKES_SITE:DARK_FORTRESS]
[TOLERATES_SITE:CITY]
[TOLERATES_SITE:CAVE_DETAILED]
[TOLERATES_SITE:DARK_FORTRESS]
delete those 2 lines :
[TOLERATES_SITE:CITY]
[TOLERATES_SITE:CAVE_DETAILED]
And goblins will no more go to live in dwarven or human civlizations
Now coming from this, a part of the fun will be bandits group, that sometime mix goblins and other species. With goblins being [CRAZED] it means internal fight will happen with non goblin bandits
And it should help too with goblin sites overpopulation, as there are tons of trolls in there, and with gobs being [CRAZED] it should help reduce those silly overpopulated locations