Yes, nested lists each count.
If that is your only issue, then feel free to increase the 50 to 200 by adjusting the settings:
defaults write com.stairways.keyboardmaestro.engine MaximumSimultaneousMacros -int 200
Keyboard Maestro has no specific hard limit for this - it is just highly unusual to have such deep nesting across multiple simultaneous macros, and almost always indicates that your macro has gone recursive.
I don't believe you'd have any performance issues for Keyboard Maestro even with 200 simultaneous macros like this, mostly doing nothing.