Emerald Dragons released on the 10th of October, first EU gate opened 30th of January.
That's 112 days of dragons, average ~6 days spawn time, 4 dragons per spawn. That's (112/6*4)=74.67 kills assuming they were killed swiftly, so let's round it down to 70. Most realms did not open the gates on the 30th of Jan however, the middle of February or later was more likely, leading to way more dragons.
Let's compare this to Kronos. Dragons will release on the 14th of February, and War Effort on the 21st. For the fastest realms it took 27 days to get through the War Effort, but Kronos is not as active as those were, so let's increase the time by 50%, that way we're overestimating rather than underestimating. So 7 days between Emerald Dragons and War Effort, followed by 40 days of War Effort gives us 47 days of dragons. The first 14 of those will have 14/6=2.33 dragons, the next 14 (14/6*2)=4.67 dragons, the following 14 (14/6*3)=7 dragons, and the last 5 (5/6*4)=3.33 dragons on average. And this is assuming they get killed the same instant they spawn, so in reality the number will be lower. Thusly Kronos is likely to have approximately 17.33 dragons or less, compared to retails 70+.
The raiding guilds on even the fastest realms of retail will have had approximately four times as many dragons to kill in order to get their NR gear from compared to raiders on Kronos. This will not be a realistic reflection of how it was on retail, and you should consider trying to get a number closer to that of retail, for example by having all 4 dragons spawn right away, instead of the slow incremental spawn system you have suggested. This would increase the number to ~31.33 dragons, or ~28.33 if you only want one to spawn the first time. This would still be less than half of what retail had, but a lot closer to a proper representation.
Of course this is using a boatload of assumptions, estimations and averages, but having the number be approximately four times less than the expected is definitely not within the error margins.
