#74 & #75 - yes this is actually a good idea and looks well - unfortunately as I have learned the tick sign is not culturally independent. In some countries a tick mean correct, inn others it means a ticking off which is bad. So this unfortunately cannot be used for a certification mark. A pity because both these logos look good!
#76 - the three elements work well together - graphic font etc, but they seem a bit unbalanced with respect to size etc. Perhaps increasing width of certification text, and making graphic a slight smaller might start to work. WOrth a try ?