At this point, a legitimate question might be: If there is no such thing as linear time in 4D, there are no frequencies, vibrations or resonances either. Could then the use of those terms by the C’s just be a “figure of speech”?
That's a really interesting point.
On one hand, I think there may still be linear time in 4D in some sense, but the 4D beings are not limited by the 'one-directionness' of it. Like when you watch a movie - the movie has its sequential time line, but you can go to any part of it, rewatch it, and so on. So for things like light, it might still work in a similar way as here. But hell if I know.
On the other hand, the things the Cs usually mention in this sense may be different all together. I think they usually apply this to the mind and emotions and things like that, in which case the 'frequency' might be something a bit different than pulses per time. Not sure how the frequency of emotions or awareness would be measured, but I suppose it doesn't require time.