What I get from this is basically that the seeming inconsistencies in scripture about which day was the passover (the Lords Supper or the crucifixion) are probably there purposely to have us make the connection between the Passover and both events.
Based on the information, I think it would definitely be fair to say that that is the interpretation that the church wished to convey, especially as most of the writers were writing to try to make a connection with and convert a Jewish audience.
Given the widespread use among some churches (not sure about Catholic) of having “Christian seders,” I found particularly interesting the info that much of what we associate with the seder today wasn’t practiced at the time. I wish I could find a timeline of the development of the different activities.
Since the Jews give a very different meaning to those parts Christians are redacting, seems a pretty clear indication that they definitely weren’t intended as a foreshadowing of Christianity, at least by the Jews.
If you are interested in learning more about how Jews celebrate Pesach (Passover) try
angelfire.com/pa2/passover/sephardicandashkenazicpassover.html talks about the differences between seder practices in the Ashkenazic (Eastern European) and Sephardic (Iberian peninsula) Jewish communities.