"I can't give you the information because obtaining the legacy would become very troublesome if the Gold kingdom Royalty gets involved," Alex said, telling the truth as lying will get him permanently killed.
Alex didn't lie about anything, as acquiring the legacy would be nearly impossible if the Gold kingdom Royalty got involved because a major part of the legacy was in the collection of a person that hated the Gold kingdom with every fiber of his being.
The {Archmage Goldfridus} legacy was bound to his treasured magic Grimoire, an item of Mythical quality that was broken into three books, and one of those books is owned by a wealthy merchant who hates the Gold kingdom.
Alex would rather collect all three books himself than give the information to the Royal family, who would flip the whole human continent to get their Ancestor's legacy and may mess things up in the process.