We all do things differently, but you need some ventilation in or close to the bottom and ventilation as high as you can get, your box seems to have it more in the middle.
The reason I say " as low as possible and as high as possible " Is because ( JMO ) when the bees are curing the honey they fan the dry air over the nectar where it picks up moister and becomes heavier, it will then fall to the bottom, if you have a bottom vent or screen it exits the hive, in doing so it creates a vacuum which pulls the dry air inside hopefully from the top so it doesn't have to be redirected by the bees. Where you actually place the vents are your decision, people have them all over the place. On my TBH I now place my entrances ( four 3/4 holes ) over my hand holds and just under my cover, the top of the hand holds are the landing board, I have partially screened bottoms.Thanks Stan. Should I put another hole on the cover, on the gable?