Let's go back to your OP, Jilly.
When West alerted and explained 2NT as a relay to 3
♣, was there any indication from East that he didn't expect that explanation?
Whether there was or not, this is the point where Law 16B1{a} kicks in. Did you "reserve your rights" or (better IMO, though not strictly "correct procedure") solicit the opponents' concurrence that the explanation may have passed UI? (Failure to do so does not impact your rights).
The TD, called after the 4
♥ bid (16B2), told you to call him back at the end of the hand if you felt damaged (this is the correct ruling at that time, of course). Did you call him back? If not, why not? If so, what was his ruling?
You said in a later post that "East must bid game". He did so and you still think he used UI. I'm confused. Did you mean "East must bid 3NT"? If so, I disagree. It does not seem to me that 3NT is an LA. Of course, it would be nice to know what East intended by 2NT, and whether West's description of their agreement as to its meaning is correct. Heh. I was going to say "is accurate", but then I remembered Sally Field in "Absence of Malice": "It isn't true, but it's accurate".
You asked, in effect, how best to handle these situations. As the above implies, I think the answer to that is that you should, at the time UI may have been passed, ask the opponents if they agree that's the case and remind them, if they do not agree, that it's legally up to them to call the TD. If they don't call the TD, call him yourself, and ask him to read Law 16B1{a} to the table. Then later, at the end of play, call the TD and suggest that you believe you may have been damaged by offender's choice among LAs (don't say "he (may have) illegally used UI" some will view that as an accusation of cheating) (Law 16B3). NB: strictly speaking, the NOS are not required to assert they have been damaged, only that the offender may have had a logical alternative to the call he chose, and that the call he chose may have been suggested by UI. It's up to the TD to determine whether the OS gained advantage from the call in question.
Another point: if there is a dispute about whether there was UI, and the TD is called, he should rule on that question. Only if he rules there was UI does the rest of it possibly come into play later. If he rules there was no UI, then you have no basis in Law 16 to recall him, because there can be no use of something that did not exist. Bottom line on this: if the TD
doesn't rule on the question, ask him specifically to do so. Of course, if the OS agree there was UI, all this is moot.