Ex BA IT here, though not directly involved with the FLY/CM programme per se. I’m not sure why it never made it to certain outstations, but one of the magic bits of FLY and the architecture behind it was to significantly reduce the calls to Amadeus. Every time to you go MMB, check in or do something at the airport, the interface weather that is BA.com or FLY makes a call to the Amadeus reservations system and BA is/was charged for it. FLY was supposed to reduce the number of requests dramatically saving millions whilst increasing system Performance.

It’s that architecture that was incredibly complex (but genius at the same time) to be able to achieve that goal. The running joke was that if you sneezed too hard, it would fall over.

To be clear, this was decades in development - it started well before Cruz’s time, I dare say even before IAG was formed.

Anyway I was shown the door a couple of years after it went live, so not sure what has happened or what’s changed in the interim. Probably makes sense to go with an industry standard solution though now of the shelf systems are catching up.