No, using Tc does not change were the ships end up when you go back to no Tc.
The Sh3 game engine will filter out the presence of ships and planes, the higher Tc the less units. Only thing I can think of would be if you use high Tc while intercepting and the game then recalculates the presence of ships you could get random results regarding what ships their are. But the convoy follows its planned course.
Maybe Bigboy can explain this better?
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