Yes, the word "lost" is ambiguous, but I didn't even notice the ambiguity until you pointed it out. I think the presence of the word "found" in the same sentence lead me to assume the "unknown location" sense rather than the "destroyed" sense.

Yes. Generally, if you know where it is, it is not lost. If you don't then it is.

But, it also depends if you want to know where it is. If you don't know where something is and don't want to, its not lost its discarded.

Another usage of the word "lost" is to indicate when the spacecraft has become dysfunctional. Although, that one is the verb form, not the adjective.

Lost can be not knowing where something is or to no longer have it.

"Lost at sea" and "lost with all hands" exemplifying a ship sinking, precision to place is neither denied nor supplied.

It's a net loss to the fleet, the shareholders and the insurer. And of course wives and children.