Yes, “through” and “via” are synonymous in the sense of “by way of” and “by means of,” but the appropriate usage depends on the sense, tone, or language register desired by the writer. In particular, there’s no question that “via” is the better choice when the statement is about a specific route to a destination, as in “This flight is bound for Los Angeles via Seoul.” How awfully unidiomatic it would be to write or say “This flight is bound for Los Angeles through Seoul”! On the other hand, it would be iffy and false-sounding to use “via” in a statement like, say, “We suggest you course your recommendations via the proper channels.” It’s much better and more natural-sounding to use “through”: “We suggest you course your recommendations through the proper channels.”
