1) Ventilation. Roof vents seem to do nothing for air flow. Might as well add a sauna class service to the trains. They are way too hot in the summer for crews.What are the current problems with the baggage cars?Nippon Sharyo could still come out of this looking good. A redesigned car could pass all tests and a speeded up assembly line could get get the cars out in time. CAF has no chance of ever looking good, since it seems the already completed baggage cars have their own set of problems.
2) Poorly designed bike rack installations and locations. There is a new configuration running in one baggage car right now. Eliminates the requirement to drop the bottom shelf to mount a bike. Also consolidates the bike rack locations to the ends of the car. Maybe it'll test well and roll out to the remainder of the fleet.
3) General wear-n-tear issues I wouldn't have expected in just one year of service.
These are just from an end-user's perspective. I'm sure mechanical people have other issues, too.