What school did you apply to? Business and marketing are in Questrom, Econ in CAS. CAS is probably less competitive/has a higher admit rate but both Questrom and CAS are reaches. For Fall 2023, Questrom acceptance rate was 8%: Questrom Facts at a Glance | Questrom School of Business
BU doesn’t specify that LoRs have to be from a core teacher, and only one is required. Not sure if they will accept two. You do need to check all the other schools you are applying to, because some will want core teacher LoRs, and I would not consider either of those core.
I can’t chance you but wish you good luck.