Roger,
You got it! I had to stare at the various components (P60, P62, P57, DE9) for a while to really understand what was going on and, as you point out, the key point of confusion is the fact that pin n of P57 is not pin n of the DE9 when connected with an unaltered ribbon cable.
The good news is that P60 & P62 provide the ability to setup either a DCE or DTE on the DE9 simply by jumpering using wire wrap as long as the P57-9 to P57-10 soldered wire connection is made.