Good to hear, questions are always welcome, just trying to offer other solutions.
My understanding is the bare transformer is the same as the one in the box with breakers etc.
I think the diagram is showing the wire nut to the L2 live. The caption referencing neutral is just showing 120v from L2 to neutral, not saying to connect L2 to neutral. If the second diagram added a wire nut to L1, it would be essentially the same as the first?
But why not wire that heater to 240V and spare a LOT of trouble? That heater is a huge imbalance and I'm surprised the inverter even tolerates it ...grainger has several 240V, 750 & 1,000 w elements, and then you could use a fairly smallish (lower losses) transformer,by
shifting the big 120v loads, to 240V. Maybe the microwave & blow
dryer would need a larger transformer to support them but how many hours
do they actually run, and is a $500 transformer worth $20 of
I'd send that element back to Grainger, it should have a +10 year lifetime