Calmag cant hurt, it should help. Your medium is staying wet too long though which doesn't help with calcium aswell. I wouldn't dose the calmag if the plant isnt needing water or it will only make it worse.Bet, so I should or should not get cal mag?
Cut back on the nutes for sure and give just a feed of calmag next watering. Foliar feed of calmag could help too especail with over sturated soil.