The other fundamental issue I see is that, even if one was able to generate an Alcubierre bubble somehow, it would be entirely useless for all practical purposes. For starters, there is no practical way to control how this construct propagates - you couldn’t change its direction of propagation after it has been created, or even slow it down and bring it to a halt relative to some external reference point, by any means I can think of (excepting perhaps non-linear interactions with strong background curvature, which isn’t practical). The other awkward problem is that the “walls” of the bubble would constitute a region of extreme curvature, so anything entering or exiting the warp bubble would be ripped to shreds by tidal gravity. Lastly, once created, I don’t see any way of collapsing such an Alcubierre bubble again; effectively, any ship in the interior would end up being trapped forever. One must also wonder what the vacuum in the interior of the bubble, and especially around the walls, would look like from a QFT perspective - Unruh radiation?
All in all, it is an interesting concept from a purely academic point of view, but wholly impractical as a means for FTL travel.