Step 6 puts the reconciliation reference in the subject or footer, and Step 5 hands the reviewer an Edit branch over exactly those two fields.

That only bites in the one case the reference exists for. A reviewer rewrites the subject, drops the ID without knowing it was load-bearing, the send then times out into send_unknown, and the search you planned has nothing left to match on.

The If node that already rejects an Edit with no body is the cheapest place to also reject one that no longer carries the reference. Better still, compose the final subject and body yourself from the approved values plus the reference, so it never sits inside anything the form can rewrite.