When CASR 66 comes in a CASA B2 covers full electrics. So if you had a CASA EIR licence you will get a full B2. CASA isn't giving restricted/limited B1 to cover electrics like EASA does.
You say your hubby has UK full B2 then CASA can only issue him I and R. His B2 doesn't cover full electrics hence CASA can't give it to him. He would need to have a restricted B1 to cover electrics from section L days or a full B1.
hope this helps.