The background signal is so large, it is hard to evaluate on its own ...
All the trappings of the D&D world obscure most game systems. Trappings means all the things one does in D&D ... monsters, negotiations, minions, maps, magic, heck even dungeons.
I watched a number of videos about the "game system of the day (tm)" ... and .... in most if not all ... you can't tell what game system they were running.
They were just playing the part of D&D that wasn't the dice rolls. Some games, the dice were the same.
In CFNG, it takes multiple skills going "on the board" to combine for various results. One player could set the next person up. Two weeks ago, it seemed we put everything into play and then moved one skill by magic. This week, we were selective since we had more choices.
There was a lot of analysis work by the players to determine which combo is the best and how to build to that. The younger guys would appreciate that.
One of the old adages is the players would do the thing that was the easiest to do. That's why they swung the sword rather than punch the fist.
I was going to suggest rather than writing a detailed mission, use a simple mission generator. (You sort of did that anyway.) Once the newness of dicing a quick mission went away, the focus could be on the mechanics. Then, each test starts with a blank slate.
As noted, the Referee observer affected the test by using material with an expected result. You could have been playing any system and the whimsy and prep would seem similar.
Another data point would be using the D&D material with the new mechanics and evaluate the results.
Who has time for that? Best to just take time and yell at the weeds.