According to Airfleets.Fr (I know, not always reliable!) EW has 7 A330s in its fleet, all A332s.
So, why doesn't OO-SFB remain at SN now (even with the CX interior; I'm pretty sure it's not that bad!) and one of SN's 4 A332s go join the 7 A332s at EW?
Seems logical, but that might be the reason of course!
[If I remember correctly, SFX is currently the only A333 able to fly to/from BOM with full load; SFB would be too!]