Hopefully there is a lurker who will read this
because, IIRC, the tool used to have an enquiry form but I cannot find it now
The fare rules allow a surface segment between TC2 and TC3
However, if the surface segment is between Europe and S.W. Pacific, then the tool includes an extra continent in the fare.
Examples I have tried are:
Europe-Sth Am-SWP (surface) Europe - prices as 4 continents when only 3
Europe-Sth Am-Nth Am-SWP (surface) Europe - prices as 5 when only 4
(if the surface segment is between S.W. Pacific and Africa, the prices are correct; expect it would also be correct if the surface segment is between Asia and either Europe or Africa, but didn't check this))
Update: found the on-line enquiry form (in the FAQs). Have submitted an enquiry