Are absences empty / conceptual constructions, according to all Buddhists?
Are absences empty / conceptual constructions
I thought this answer implied that an absence is unconstructed:

So the absence of remorse is conditioned, but not being an existing thing, not having been constructed (sankharaed)-- it was the result of not-doing, is not itself subject to ending and is a small taste of Nibbana.

is it -- perhaps -- a fact independent of language that there is no elephant in this room?
I don't know -- sense-contact with the room gives rise to various perceptions, but none which I would label &quot;elephant&quot;.
they are devoid of causal powers
You're saying that as if that's a bad thing. :-)