Only frustrating to the railway cognoscenti. To the general public, FRONT is the first one you come to. REAR is the one at the back of it.
The Southern cracked this long ago for their many portioned trains, it was then "4 coaches nearest the barrier", along with "4 coaches furthest from barrier". Useful expressions probably eliminated by the same managerial approach that finds leaving the passengers out on the platform, when they could be comfortably sat down waiting for departure, is somehow a good thing (see multiple posts above).
If you're coming from one direction at a barrier line at a London terminal for instance, I think its very very difficult to confuse Front & Rear. That being said, normally its followed up with manual announcements "...further from the ticket barrier". Something I've done before as well as "please walk further down the platform to board this train".