I have not tried it before, but there are probably a limited number of parameters which could be iterable. Can you share what parameters you are iterating in the timeline and an example project, so I can test it?
I have this working during runtime for x,y,z rotation and scale, but it does not yet work in editor, I am asking Scirra about this possible limitation:
https://www.construct.net/en/forum/construct-3/plugin-sdk-10/editor-support-time...