The problem here is quite simply that the e-ticket receipt specifies the allowance for OWS. However, the relevant date for baggage waivers (and other perks) is the date of travel. OP says that he was OWR and that is what applies to his ticket.

Bear in mind that the DOT rules regarding baggage for tickets originating or destined to the US is that the baggage allowance of the marketing carrier of the first segment applies to the entire ticket. But, it does not apply as to waivers for status and the like. Hence, either AA or BA would have properly collected the fees due based on OWR.