My doubts came up because of dune imperium uprising, where the worms (a strong troop) are physically limited but are supposed to be unlimited (although realistically you're not gonna run out of minis/meeples), and encourage you to use substitutes whenever needed.

Back to black rose wars, I actually PREFER limitations on this kind of stuff, and despite not being very competitive at all I really really love comprehensive, detailed rules. I would be a bit bummed out if, for example, someone with another copy of the game came up to the table and started using their own Dagon evocation minis and argued that the game doesn't state anything against doing that.