The problem is that you are not picking shrimp instances inside the functions. For example, in "state_walking" function you need to pick shrimps with currentState="state_walking".
Also, in event #2 you need to add For each Shrimp. Otherwise this event will trigger only one function - mapped to Shrimp.shrimp_CurrentState of the first shrimp instance.
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I am not sure why you need to use mapped functions here. I think you misunderstood what function mapping is, it doesn't map functions to instances with specific values in instance variables. It merely allows to call functions by their string names.
So you can do the same by simply picking shrimps with each state on every tick:
On Every tick
Shrimp state = idle -> ....
Shrimp state = walking -> ....
Shrimp state = dead -> ....