There is NO school in California authorized to do MODULAR JAA CPL or ME-IR training
Very true, not authorized by the CAA. However you're doing American ratings to the higher of JAA or FAA standards, with a view from the outset to convert to JAA. The way it works is you do FAA CPL/IR (or just IR, whatever) then head over to the UK and do a couple of weeks to an FTO there, where you take the conversion flight tests / training. There is no fundamental difference between flight in Europe or the US, there are however different procedures, tolerances, and rules, and if you can fly to these before your trip home, then the conversion should be possible in the minimum required time.
Cheers
EA
PS> Do you really know ALL the schools in SOCAL?