you need to be consistent about accepting "large" as a synonym for "big" and "shop" as a synonym for "store". i can't read your minds to guess whether it's going to be allowed in this example just because it was allowed in the last one.
What about "I am looking for a great store." When I see великий, I think of the Great Gatsby.
It is more natural in English to say "I am looking for a big/large store" or "I am looking for the big/large store."
Is it a question or a statement? :D
None of them is more natural. They just mean slightly different things.
Both are accepted here.
I found out from several Ukrainians that магазин is a Russian word and that the Ukrainian word for store is крамниця. I was hoping to learn only Ukrainian words in this course.
Technically it is a Ukrainian word, because the modern Ukrainian language was influenced by Russia and other Eastern European countries especially during the Cold War era. Therefore, by this course teaching the "modern" language of Ukraine, some words and phrases will be different from the more traditional language, and other various dialects.