With CX, you'd get 75% of international school fees, or 90% of ESF fees.
No idea about KA... ...and you gotta pay tax on that too..although it sounds great you will be short by 15%...
It costs me approximately HK$480 000 pa to send my two kids to a good school in HKG. The "assistance" with school fees is based on school tuition fees alone, which are only a portion of that total cost. So my reimubursement of 75% of international school fees only covers approximately 50% of the actual cost.
The real problem is not really the cost but actually getting your kids into a good school in the first place.
A key reason for becoming an expat is to improve your lifestyle, and getting your children a good education is a key part of that.
Ensuring this is now very difficult for new comers to HKG. Unless they are billionaires from over the border.