Thank you, Bhante, for this clear elucidation.
This seems to align with the way in which Bikkhu Bodhi uses the term "gandhabba" as referenced in the OP, namely, as relinking consciousness. And I believe you get right to the heart of the matter by highlighting both the conventional use of the term as well as the ultimate use. It's so easy (for me any way) to blend the two together and arrive at an imprecise understanding.
With regard to the conventional truth, if gandhabba is a being, then does that constitute an intermediate state? And would that introduce the notion of a mechanism to help arrive at a conventional understanding of how gandhabba can accomplish contact with the embryo from vast distances away? Or would this be going down the road of speculation?