I see.
About the GUI. It is a bit difficult with the network id, since it can change whenever a connection changes. In theory it would be possible to add such statistic,however the user would need to know which network id belongs to which actual network at that point in time. Also it'd help to know which stats are then interesting. However it doesn't have much to do with Electric Transformers, we'll evaluate your idea for implementation. This functionality would implemented with another mod.
IRL the industrial transformers for power conversion dump the load and have generally few safety mechanisms which prevents them or the power lines to go up in a flash. Would be possible, but would require maintenance tasks in-game no idea if that is adding or destroying the game experience. Automatic dropping/resetting is even more weird logic since can have various unwanted side-effects. In general for ET, yeah, smth can be done with the overloading case, however we need more information on what should how happen and when. As the transformer would work more like safety device, the power poles wouldn't explode. I thought about simply disconnecting the wire on that line in question.
We'll look at that compatibility issue with "useful combinators".
Regards,
-max2344