It would be very difficult for me to believe that the crossover dip was an oversight by the JBL crossover design team.
While ASR is good at measuring and complaining, I’ve yet to see them do an in depth speaker analysis. They measure a speaker, sure, but an in depth look would be to disassemble it, trace out the crossover, measure the driver impedances and then put together a complete simulation.
Or even better, do as Troels Gravesen does with some vintage speakers and demonstrate the value of a crossover re-think by making a new crossover and measuring the finished results. ASR is a misnomor. They are Audio Quality Review... they don’t usually know what the underlying tech is doing, they just measure the results, which is useful but doesn’t go far enough. For instance, the Kef Reference 1 Meta really needs an in depth crossover analysis because there may be great ways to fix the low impedance. ASR noted the impedance without any understanding of what they were looking at.
My point is, they measure, they get all huffy and the like to think of themselves as the last word, but they are not even close.
It is quite possible the crossover is the best compromise possible with these two drivers. I would be absolutely shocked if this was merely a matter of crossover selection. Not in this century and not from JBL.