"The Installer has no way of knowing about downloaded and separately installed Updates. It must install the version that was in there at the time the Installer file was put together."

True--except that in this case the version of the application on the UltraPak disk is itself newer than the one that got migrated to my laptop. That, the Setup program could check.

In any case, users of BiaB could benefit, as we do with lots of other apps, from a "Check for Updates…" menu option--or even an automatic check, like Adobe apps and BBEdit and so on. Then a Setup program could tie into it, running the check after doing the installation.