You forgot to account for the fact that the second Castle also provides +2 Cyclops (unit increase per Castle).
That is, 2+5+5+10=22
Which is a significant imbalance, as Inferno and Elves have a maximum unit increase of 7th level +14 per week.
In the second Castle, I prohibited the construction of the Cyclops cave, which gives 22-7=15
Balance restored.
Here is the new version with the corrections made.