Help debugging this circuit, voltage across lights drops to half unexpectedly. Diagram in post
You have your transformers in series they should be in parallel, sorry I could not keep reading and all the comments. With the transformers in series the output voltage will be 1/2 . Connect the transformers in parallel and your voltage will double. 
I don’t think your before drawing was accurate. I have seen this done many times by new DIY folks trying to add lights.