You could use a FeedbackLoop with Framelength samp delay for the summing. Divide all incoming values by the number of frames you want to average (for example for an average of 30 frames use a gain module with 1/30 gain before entering the FeedbackLoop). For a running average you should subtract frame 1 after 30 frames, frame 2 after 31 and so on.. use a delay with FrameLength * 30 samp delay time and a difference module inside the loop to accomplish that. I'm not in front of Kyma right now to post an example, sorry.
OR what you really want is possibly smoothing? You can do that with the SpectrumModifier, have a look at the description, it's straight forward.
Let me know how it goes!