Which CF6 are you speaking of (and on what aircraft)? If you're talking the CF6-80C2 FADEC on a 767 or 747-400, auto-relight is basic.
Continuous ignition at high power doesn't do anything - above a certain burner pressure the electrical resistance of the air is such that the igniter can't spark and the electrical energy simply dissipates through the ignition components (which is really abusive to the system). The latest FADEC s/w on the CF6-80C2 767 and 747 installations actually inhibits ignition if the burner pressure is above a threshold.
Most newer installations (e.g. 777, 787) no longer even have a continuous ignition switch - auto-relight has been certified to be equivalent.