[The Rider]

maybe there is a collision between the negative morale line for emerald dragons (-2 when giants in army) and that line. Not sure if it is not a copy-paste error but the command line should be like this:

giant {
alchemist,cannoner,dwarf,miner,miner2=+1,hint_mora le_commander
}

and not like this

}
giant {
alchemist,cannoner,dwarf,miner,miner2=+1,hint_mora le_giant
}

because with the first } you are closing the unit2unit tag. you can skip also the text after the // since it is only a text comment. Also for the hint it is better to use hint_morale_commander than hint_morale_giant. The first one says "Commander presence" and the second one is used for the negative morale for the emerald dragons.
here is a larger example for unit2unit:

unit2unit {
knight {
knight=+1,hint_morale_knight0 // повышенная мораль
}
greendragon,blackdragon,reddragon {
gorguana,gorguana2,gobot,gobot2,chosha,brontor,dig ged_brontor,highterrant,tirex=-1,hint_morale_dragon // Драконы в армии, Ящеры их ненавидят и взаимно.
}
greendragon,blackdragon,reddragon,bonedragon {
griffin2=-2,hint_morale_dragon
}
tirex {
gorguana,gorguana2,gobot,gobot2,chosha,brontor,dig ged_brontor,highterrant=+1,hint_morale_tirex // Ящер-Защитник
}
robber, robber2 {
peasant,bowman,footman,priest=-1,hint_morale_robber //Присутствие разбойников в армии. Мораль -1
}
footman2 {
bowman,footman=+1,hint_morale_commander //Присутствие командира в армии. Мораль +1
}
giant {
greendragon=-2,hint_morale_giant //Присутствие Гигантов в армии. Мораль -2
}
greendragon {
giant=+1,hint_morale_green //Присутствие Изумрудных Драконов в армии. Мораль +1
}
giant {
alchemist,cannoner,dwarf,miner,miner2=+1,hint_mora le_commander
}
blackknight {
archer,Skeleton,zombie,zombie2,ghost,ghost2,vampir e,vampire2,bat,bat2,necromant,spider_undead,bonedr agon=+1,hint_morale_commander //Присутствие Полководца Тьмы в армии. Мораль +1
}
dryad {
thorn,thorn_warrior,kingthorn,ent,ent2=+1,hint_mor ale_driad //Присутствие дреесной феи в армии. Мораль +1
}
ogre {
shaman,orc,orc2,goblin,goblin2,catapult=+1,hint_mo rale_commander //Присутствие командира в армии. Мораль +1
}
druid {
dryad,elf2,elf,ent2,ent,sprite_lake,sprite,unicorn 2,unicorn,werewolf,wolf=+1,hint_morale_druid //Присутствие командира в армии. Мораль +1
}
unicorn {
dryad,sprite_lake,sprite=+2,hint_morale_unicorn
}
griffin2 {
griffin,griffin_spirit,archmage,bowman,footman,foo tman2,horseman,knight,peasant,priest,priest2,robbe r,robber2,paladin=+1,hint_morale_griffin //Присутствие королевского грифона в армии. Мораль +1
}
}

I checked this and it works just fine.
edit: dont know why this forum makes slight changes to the code adding blank spaces in some words. If you are using the KBmasterMod make the changes in the mod file, not in the session.kfs