Thank you much for your reply.
I am new to Role playing games (having played D&D once as a hero). I have chosen to try my hand at Grimm being attracted to the streamlined ability system of Grimm. My background is in boardgames so I am used to more "rigid" story-telling and mechanics. I can see that a malleable time system empowers the narrator to design the narrative. Not to mention that the whole system is malleable overall. I am looking forward to finding and making use of this freedom as a narrator.
If one were to set a round to a specific length, 3 seconds seemed right to me. Actually I wondered if I had read that in the rulebook and just could not find it again (I was looking for that before I posted here).
and, Yep, that was what I was thinking concerning the imaginings, although I had forgotten the difference between environmental and item imaginings. It is good to here my understanding confirmed. Thanks.