Dark Elves economy un-playable, and where are monster units?

I'm now playing on turn 50 on VH/VH with dark elves. I have "beastiary" building where they are suppose to manufacture Hydras and Black dragons but they are not available.
I did check the export_descr_buildings and in there it reads "and hidden_resource dragon" ??? What the heck is that, and where is it's location?

levels beastiary_1
{
beastiary_1 requires factions { spain, scotland, sicily, milan, saxons, byzantium, france, hre, venice, portugal, papal_states, russia, mongols, } or factions { england, } and hidden_resource dragon
{
capability
{
recruit_pool "hydras" 1 0.056 1 0 requires factions { mongols, } and hidden_resource dragon
recruit_pool "black dragon" 1 0.056 1 0 requires factions { mongols, } and hidden_resource dragon
recruit_pool "Dragon riders" 1 0.056 1 0 requires factions { england, } and hidden_resource dragon

I did actually delete that "and hidden_resource dragon" from the folder, but they are still unavaible. How I can acquire them? I really want to know.
---

The other thing, DE economy.
With default settings player will have constant negative income due to all heavy cost upkeep units and ships. Test played this for 20 turns and no change.
I solved it myself by cutting every dark elf unit upkeep by -100 gold, and the for all ship types upkeeps I decreased from original 600 to 300. Only now DE economy is able to thrive.
Start is slow. but after few, 5 to 10 starting turns person is able to make economy to plus +2000 instead of -3000

The hidden resources are assigned to provinces in the descr_regions.txt file (in: data/world/maps/base). By default the dragon resource is assigned to Naggarond, Tor Sethai and Lothern, so you can only recruit dragons in these 3 regions (for lore purposes i guess). But it should work once you removed the requirement of the hidden_resource dragon. Hmm strange... Keep in mind that you need to delete the map.rwm if you want to make any changes to the descr_regions.txt file and let the game generate a new one.

Is there a particular reason why you expect the dark eleves to have positive income from the start? It's fairly common in mods to have factions that start with a built up military force that costs too much and consequently forcing the player to choose between using it quickly or disbanding enough to make the costs bearable. I don't have the latest version of the mod but the dark elf society is built upon slave raiding and in constant turmoil and near-constant preparation for the thankless invasions of Ulthuan, so it would make a lot of sense lore-wise to have them start with a large force already recruited, ready to set sail and pillage.

This one is a little tricky...
The problem isn't the hidden resource, you need a settlement_min large_city to build the Bestiary, the Dark Elves only have level city.
If you change to settlement_min city, the other factions can also build earlier, not good.
Only Lothern, Caledor and Naggarond have the hidden resource dragon, so change the recruitment to another building, like the elven_stables_4, that's what I've done in my campaign.

It's actually a little odd that the noble dark elves have cities instead of castles for home settlements. Their cities are clearly described as favoring towers rather than width and some are built in some rather confined locations. Castle type settlements would suit them more I think, although no Medieval II town type really do them justice.

The Druchii castle model is a custom settlement, but the Level is city, it's how the game is designed, from the descr_strat.txt:

settlement
{
level city
region Naggarond_Province

It's just a definition, in the campaign they are Castles! ;)

Well, I solved my monster availability problem by adding those black dragons and hydras to stables buildings, without hidden_resource dragon requirement. Had fun with them as Ulthuan AI elves also made and sent their own dragon counterpart against me. Had blast fighting against them. Being available every 20 turns and costing a lot 6000gold made them still rare sight.

I wouldn't say vanilla DE campaign being fun as play-testing first 10 turns your economy is running minus -20 000 gold, being unable to make anything. And distance to send your armies to Ulthuan is huge and at early game rebel cities won't help overcoming that -20000 debt.

By cutting -100gc out from every DE unit upkeep I managed to stay in plus, but still I had to think how to spend my money, and had to save it to acquire those monster units. I did eventually defeat ulthuan elfs and Lizardmen as well. I think it took ~100 turns for me. Now at turn 133 pallning to raid Bretonnia next

Of course AI can manage with DE that as very hard AI economy never allow their economy going to red, and gives money to get out from red money zone. I didn't use money cheats during my campaing.

An alternative approach is to actually disband some of the redundant starting units. Naggaroth is well protected by its remote location and the costly hordes of corsairs from the start are not needed to defend the home territory.