Most regional UK fields have PAPIs or VASIs so if you teach your student to fly these then he/she will round in the right place. Agreed that without these or from a flapless (flat) approach you need to use the threshold as your aiming point.
Your actual touch down point should be as far away from the round point as possible. The best touchdowns come from trying to keep the aircraft flying as long as possible, even in a trike configured undercarriage. Alas some pilots don't do this and end up in the accident reports with broken nose gear.
Vigi