I believe the new missing mage is a different person. That one ran away with teleportation tech, not a spell, that the gov't was funding. The grand mage's lover went missing 40 years ago and is presumed dead. In the chapters missing from here, the ML makes the connection between the missing lover, a girl (I believe from the slums), and the story the FL told him about her grandmother. Iirc, the new mage's disappearance is just what prompted the ML to look into the grand mage's lover and cut funding for the magic department
I can rip the chapters and upload them here if you'd like, but the links are posted in the comments here. There's not actually 25 chapters, Artlapsa just cuts them in half

I don't understand, the grandma is his missing lover but is also the grand mage who disappears because was studying teletransport, how?