Thanks for playing and we completely agree with both of your suggestions.
The whiteboxed level was initially larger, when we weren't quite sure where we were going with the story and we did have to massively cut it down by the end of the jam as we were narrowing down on the plot & also having to descope other gameplay/story elements.
As you wrote, with such a large level, we did shoot ourselves in the foot a bit in terms of playtesting ; the less confined your game is, the longer it is going to take to thorougly playtest and we did eventually run out of time.