This is more of a timing question. If I attack someone with a 2 dice primary, use Krennic to spend a die, can accuracy corrector still cancel the 1 die out and add 2 hits?

My reading of the timing chart and effects says yes you can, but I'm looking for confirmation.

Yes.

Since both effects (Krennic's result cancellation, and the Accuracy Corrector cancellation & result additions) happen in the modify attack dice step, you (as the player controlling both effects) have the option of activating them in whatever order you see fit. The way you describe - cancelling 1 die to remove a shield, then cancelling everything else to add 2 hits - is the most efficient way of doing it.

It'd also work in the other order. You can cancel the dice you added with Accuracy Corrector, since spending a die isn't modification. This is less relevant to Krennic than it is to Crimson Leader, who can spend an Accuracy Corrector-added hit to assign the Rattled condition to the defender.