Could it be that WEST and THE are purely coincidental in that they are the only two words that make any sense but as it is an encrypted message they have appeared by chance and don't mean anything at all. Sort of like what humans are good at which is latching onto the familiar. Saying that if that is the case then FD really are making it very hard. Shame we don't have another encrypted message where we could see if there were any repeated phrases, kind of like how in The Imitation Game where they figured each message was signed of the same way.
i'm going on the assumption that everything we can "see" and understand in the encrypted message (WEST, THE, 42.1LY) are coincidences in the encryption.