I'm not sure Jake shared the Howler's collective memory... If he had, then they could have just dumped all the memories into Jake while he was in Howler morph... They wouldn't have had to risk another encounter just to subdue one of the real Howlers...
But that just leads to a whole other conversation on just how much like the real thing the Animorphs were in morph... Did they retain their own minds? Their spirits? Clearly, when they morphed bugs, they weren't as dumb as bugs...
So... Just how much of the Howler's mind did Jake's morph have? Just the instinct? Surely not the memories...