As far as the 120% rule at the main panel you have no concerns, since there is no busbar, hopefully the diagram is accurate. It appears quite complete, so I'd be surprised if that was omitted.
However you do need a 125A or 200A main breaker inside the backup loads panel for system B.
Also, as it stands system B existing 125A subpanel is not 120% rule compliant, though it may be 100% compliant, that is not clear to me from this. One solution is to land the 11.4 inverter for system B inside the dedicated internal subpanel.
Edit: Even with the 200A subpanel it is not 120% compliant, but a 225A subpanel would make it so.[/QUOTE
Does this drawing make more send on what I tried to write?
All the existing wiring supports 200 amp I believe, It was only after county code the breaker was changed. I believe. When you say backup subpanel not sure what this means. I have had for 30 years 2 200 amp subpanels driven from the 400 amp grid feed. One for the house, one for the garage. As I said, they made the drawing wrong as terms of what the panel spec is.There is no reason the GW2 cannot be fed with a 125A breaker. Why run larger wire when the backup subpanel is only 125A
If all the PV is landing in the GW2 then there are no other 120% concerns.
Yep, solar split will land into both GW2's so no issue? Does this updated drawing reflex what I am trying to say.