As far as i can see there’s zero insulation and basically no thermal mass to buffer the heat. They’re going to need to keep a fire going 24/7.
I spent a few nights in a yurt in Mongolia. You are correct. Our fire went out at about 4 am one night and I very quickly got cold enough that I wondered for a bit if I was going to die (spoiler: it was fine).
I had the identical experience - so cold! The smell of those horse dung stoves are amazing.
However, the most memorable thing arriving in Ulan Bator was seeing two different yurts on fire. Fabric buildings containing wood (dung) burning stoves and chimneys have not looked tempting since.
Oregon is a pretty warm climate. Just eye balling the terrain, they look to be at a pretty low elevation and probably won't see more than a few weeks of below freezing weather per year. Not sure this would be practical in a more punishing climate.
A common misconception is that insulation is about heating only. It’s not, it’s about keeping the indoor climate as steady as possible, which means cool in the summer. Even a moderate summer will be balming hot in a tent.