Park Chung-hee's spelling in his letters is quite serious

In the letter written to Park Geun-hye's daughter, he uses "oen-il-ini" instead of "eol-maen-il-ini" (what brings you here?) and "ge-si-ni" instead of "ge-si-ni" (are you visiting?).
Even if he was from a military background at the time,
wasn't he a primary school teacher during the Japanese colonial period??
How can his spelling be like that? Shivers.