I think it's not a FB ticket. It's a HV ticket with partial FB payment to the tune of 100% of basic fare. This makes a difference...

Also with what they say about cancellation. I've made a dummy booking and Flex option specifically says it's changeable for free, not cancellable. Same holds for "Max" ticket option. The differences in flexibility is only for how long before the departure you can change the ticket. By the looks of it, Transavia does not sell cancellable tickets at all.

Transavia is also not a member of IATA and quite possibly does not issue IATA standard e-Tickets at all, so no 074 (or otherwise) plated ticket. The booking reference is the identifier of the internal Transavia e-ticket.