Hi

The Sub is not known if the contact is found in a direct path or convergence zone. But an TMA solution is possible only in direct path, less than 20 nm. So, after a few rounds of contact without TMA solution, the Sub will know that the contact is in CZ. Am I right?

Again I'm speaking outside the rules (what a pest I am!). You cannot assume the contact is in a CZ, you may just have a maneuvering contact that defies an easy TMA. The best way to know your contact is in a CZ is when it disappears and reappears much later, much stronger (goes away while transiting from CZ to direct path detection).