>>38868531He never faced Cynthia. That would require the anime actually bothering to explain anything about the "champion's league" and thus develop at all. Beside, he might be going through the equivalent of Victory Road indefinitely thanks to the anime refusing to move time.
It's terrible that the anime keeps wronging Ash and leaving out the second half of what Shudo intended, but "Tobias lost to Cynthia" is just a lie made from sour grapes.