This princess is incredibly incompetent. And should be treated as a pariah by MC + FL for allowing this to happen.
Who cares if she is "well intentioned". An incompetent screwup who is "well intentioned" still allowed a child to be abused, despite her explicit promises to them. Incompetent + track record of failure = no more trust or responsibility. The entire elven race deserves to have a war declared on it.
"Oops, our first elder lied to you, kidnapped your daughter under false pretenses, lied under oath of state, in formal diplomatic mission, inciting a war with a world power. ~Tehe!~ I'm sure they'll forgive us."
I hope there are some actual repercussions for this.