One more question - is there any purpose in going to T5 in person? The bags are listed as “still being searched for”.

I suspect not - I doubt I could get access to the area the bags are stored in, even though the Air Tags would give me a good steer towards their location.

Or even - book a ticket this afternoon, check in, go airside, then ask to be offloaded, go out through the baggage hall and have a look myself? Very doubtful about that!