As promised (or threatened):
I've posted a Mac OS 9.0.4 system disk image, complete with MachTen, Crypto Ancienne, and Classilla (configured to use Crypto Ancienne) and an AppleScript that launches MachTen with Crypto Ancienne and then hides the console window. You should be able to use with SheepShaver under macOS (it's a sparsebundle so it won't work in Windows or Linux):
https://mendelson.org/MacOS9MachTen.sparsebundle.zipThe system is a default-installation Mac OS 9.0.4 system, with only four things added: the MachTen folder, the Classilla folder, a BBedit Lite folder for editing MachTen configuration files if you don't want to wrestle with vi or some other unix-style editor, and the AppleScript, which can be copied into the Startup Items folder.
When you shut down the system, the MachTen console appears briefly, and then the system finally shuts down.