Efficiency Calculator: You can select all the structures you want to measure and it will return the percent efficiency
of these structures over a specified time (3 mins in ms).
Efficiency = Uptime (Time that it isnt unmanned or underpowered, perhaps choose either or)/ Total timer decided
Could even provide a graph that shows how the efficiency changes over time (Might be a burst vessel or better for sustained combat ect.), and other modifications that can improve the QoL of the addon.
This is better than trying to understand the efficiency of the position of a reactor core, which seems overly complicated. The point of reactor placement is to improve the efficiency of other structures anyway.
This will also show the effectiveness of structures like the walkway which isnt easy to judge its merits.