Current behavior is 5 inputs to 1 output. This makes no sense for a transformer from MV to LV. You'd need 5 LV outputs to properly output all the energy input from 1 MV cable. Currently this makes transporting power across your factory much harder.

LV to MV transformer is correct with 5 in : 1 out, but MV to LV should be reversed.

This could also be solved by allowing the LV to MV transformer to accept energy input on its 'Y' side rather than a strict output

This is on version 1.2.2 for 1.18. Looking at the changelog, this has not been changed in any recent release or beta versions either.

Turns out this was fixed in 1.19 already. We can't fix it in 1.18 as it's a breaking change.