You can define it that way, and sure, there's a certain difference when we borrow phrase bits from languages we don't actually understand and use them as an exp

You can define it that way, and sure, there's a certain difference when we borrow phrase bits from languages we don't actually understand and use them as an expression (inter alia, et cetera) and when we do. But the latter also happens when bilingualism is common. I won't actually consider these wholesale expression borrowings part of English until they spread to English speakers who don't speak the borrowed language.