I think it more likely that your town was in Volhynia, but only on the
basis of the transcription of the name.
My great-grandparents were >from Kopyl, Belarus. In Yiddish, the town
was called "Kapulye" and its denizens were "Kapulyer." For example,
the synagogue that was composed mostly of lantsmen in Omaha, Nebraska
was called the "Kapulyer shul." It is unlikely that somebody
rendering "Kapulyer" into English would omit the "y" or would
transcribe "Ka" as "Ki" and "pul" as "pil." However, the
pronunciation of a written "u" as a spoken "i" (e.g. kugel and kigel)
was frequent in Volhynia, which makes the change >from Kupiler to
Kipiler quite conceivable.
Of course, I'm not an expert on Yiddish pronunciation, and,
admittedly, English renderings of towns were all over the place. But
I would just put the odds on Volhynia.
All the best,
Researching Batt family, Shumsk