There are multiple customs regarding sukkah on Shemini Atzeret. Some make kiddush in the sukkah, but eat indoors; others eat in the sukkah at night but not by day, or "go inside" after daytime kiddush. This makes some sense if you consider that the "geshem" prayer for rain is on Shemini Atzeret morning, so why would you sit in a sukkah when you've just prayed for rain!
Generally one should follow one's ancestral custom. I suppose the OP would like to know what the ancestral custom of that town was. If the town or local area had a notable Rabbinic leader, then that could help find the answer.
If one doesn't have a family custom, then they would do as per their own Rabbi.