I think spies need there own separated building bank from the other unit classes. Its increases the time to build real units in bestiary class builds. This would be a good ideal.

i agree but enter conflict with imperial units.... need money for build more 

Greetings. Unfortunately, we are not considering the idea to add more building queues for Units. I understand that you would like to build them faster, and increase both: Spy Units and Bestiary Offense/Defense. However, our game balance requires some limitations, and building queues are one of the major limiting features.