Ubiquitin, the Aruch Hashulchan was a limud z’chus for a very cold climate. This does not apply in most places frum Yidden live in today.
Those who don’t sit in the Succah on Shmini Atzeres are in direct violation of the gemara and Shulchan Aruch, and should go to the succah, because minhag isn’t oker halachah.
(I know all about the zilzul issue, and I can usually read through the typos, but I thought you were mixing up “house” and “succah”, but I suppose that was based on your not knowing the gemara/S”A).