Thank you for providing your MD version and build.
I would tend to think that this is more of a printer driver issue. However, provided that you purchased Moneydance through the Moneydance website (as opposed to the Mac Store or elsewhere) then you should update to the latest build of MD 2017.10 (1706) from here to see if doing so resolves the issue. https://infinitekind.com/download_2017
Given the wide range of reports that can be produced b y Moneydance, it would make sense for the user to be able to choose the paper size for the report. The printer in this case handles multiple paper sizes, and these are supported by the driver (i.e. other apps can print to the larger paper sizes).
I figured it out. You have to click on the Print button, then choose Paper Handling in the system print dialog, then click on the "Scale to fit paper size" checkbox, and then the Destination Paper Size can be changed.