Haven't time to read the whole article now, but what I have read is interesting. Used to volunteer at Butser Ancient Farm in the time of Dr. Peter Reynolds, and have had quite a lot of contact with it since. It seems to me that the roundhouse was perfect for our climate, and that without things like hypocaust, Roman houses were impossible here. They have a reconstruction of a villa at Butser, and it is always cold and damp, while the roundhouse is cosy.
My speciality was spinning, weaving and dyeing, and it impressed me that the skill level of the Celts even in these was very high. I understand btw that silk has been found in western Europe, which must have come from China, so even more extensive trade routes that you mention.
Husband used to fire the Romano-British kiln, and produced quite a lot of successful pots once he had mastered the technique.
I am afraid I have an antipathy about the Romans and while realising the original name meaning of the word 'barbarian', believe the modern meaning fits them better than the Celts.