Points to re-emphasise ..
(a) (unless the OEM guidance has changed in the past several years that I have been out of the training arena... please, someone, tell me if things have changed ?) there is a subtle difference between what the regulation appears to say and the practical application of the regulation. The OEMs expect the pilot to have commenced the stopping process by V1 for a satisfactory accel-stop manoeuvre. A simple legalistic read of the quoted reg implies just this.
(b) changes in regs are not retrospective. For any given reg, the TCDS MUST be checked to see what the regulatory basis for certification was .. and then you chase up the historical reg to get an idea of what the story might have been for the certification .. and, in the case of performance, one also needs to review the pertinent edition of the flight test guide to see what the FAA thought the reg might have meant.
(c) re screen height, indeed, if the takeoff is continued with a total failure prior to the scheduled Vef then the screen height will be compromised. Whether this will be significant or not depends on the circumstances.