The flaw on the KH23 isn't very prominent. It's more obvious from the rim to the G, but thinner as it leaves the G and heads for the truncation in a gentle arc to the right. That is the only difference between KH22 and KH23 and arguably is just a late stage 22 not worthy of a separate number.
To differentiate KH16 & KH22, the first has a flaw under the armpit and SOHO is in line. The second has no flaw and the second O is lower. The flag on the ship is also smaller on the latter die.