The background states; You’re trained in the Warfare Lore skill. You gain access to Aldori dueling swords and can purchase one as part of your starting equipment. You treat Aldori dueling swords as martial weapons rather than advanced weapons for the purpose of proficiency.
But the character sheet doesn’t reflect that. I can’t see any way to alter the swords required proficiency or a way to directly add the proficiency. So this leaves the sword as untrained when wielded by a swashbuckler with the Sword Scion background