that's what it looks like to me- most of my belly fails have been pretty unspectacular- more of a "crink- crunch". yours looks like it was a worthy explosion.
i think you were right on track with the dimensions, but i'm firmly rooted to my soapbox on smooth tapers. with cherry's reputation for chrysaling, it seems like your tempting fate by not getting them in order before bending. but- in looking at the pics, i can't honestly say if floor tillering & obsessing on tapers would have made a difference for you on this bow. i prefer to think of floor tillering as an extra measure of insurance, and it helps me pinpoint where to focus the reflex- if a belly floor tillers a bit whippy, then i know to put more reflex in the outer limbs & maybe leave the inners as they are. if it floor tillers with too much bend in the handle, then i add a power lam.
i'm still not too trusting of maple for cherry either, but that's just me- seems like most other guys have done fine with it. you may want to check your other rips to see if there's a bit of figuring or swirl to the grain in the same spot on another rip. i guess that would go for the bellies too. i managed to overlook a check in a hickory backing strip last week that caused a R/D hick/maple/ipe trilam explosion, so wood defects are kinda fresh in my mind.
i suspect you'll get some more experienced folks weighing in on the cause of death. i don't put too much stock in my knowledge atm- i'm all hopped up on painkillers ><