Dipikaji,

I think it depends on the context. "kati parla andaaz gara ta" is Nepali "andaaz", "Usko kura garne andaaz arkai chha" is not. It is similar to the difference between "ko" and "lai". "tum usko batana" in Hindi is "timi uslai bhana" in Nepali. How does it sound if we say "timi usko bhana" even though there is the word "ko" in nepali which is used in different context like "kasko gharma jana lageko?".

Sometimes it's not just the word but the context you use it in to determine if it is Nepali or not.