I’d avoid trying to create some sort of formula that converts Zwift ratings to TR ratings. 
We did our best to ensure that the two line up as closely as possbile, but if you’re struggling to make a confident decision with Zwift’s 10 options after a workout, I’d follow @stickmandj’s advice and fill out the survey in TR instead.
That way, you have the TR descriptions to reference to ensure that you’re getting it right.
It’s important to trust your gut a bit in these situations, though.. Switching from a “Very Hard” response to “Moderate” is a big jump. The “Hard” rating also says that you would have been able to do another interval with some focus, so maybe that would have been the right choice for your recent Creise workout. 
It’s sometimes easy to say that you could’ve done more after the workout is over, but I often like to ask myself those questions right after the end of the second to last interval, right before the last one, and/or just before the last one ends. I use that response in my survey. After cooling down and getting off my bike, my emotions have usually already changed. 
