I don't know specifically about the Roman-Parthian boundary, but in D.K. Fieldhouse's "Western Imperialism in the Middle East 1914-1958" he mentions the theory that both in the Sykes-Picot and other boundary discussions the negotiators were unduly influenced by classical history. Picking landmark cities from antiquity rather than informed understanding of modern associations.

It is, as he further describes, a small part of the overall story (especially considering, as I try to emphasize as much as I can on this sub, that Sykes-Picot wasn't actually responsible for determining final status borders in the Middle East, but was actually a temporary wartime negotiating position between three imperial powers) but yes the classical educations that many of these men received clearly influenced their thinking and knowledge of the region's geography.