Many thanks for your advice @BuZz. I modified the startup script as you mentioned and it still works.
My understanding is that BasiliskII should ever load the 'keycodes' file so the host keyboard layout (the one configured in Raspbian/RetroPie, here) is taken into account, whatever international layout it is. Without the 'keycodes' file, only US-layout would be recognized and typing from another host keyboard layout (i.e French AZERTY, German QWERTZ...) under Basilisk would produce weird result. If I understand well, the keycodes file contains the USB keycode for any environment BasiliskII has been built for (so, the Linux framebuffer, here).
By the way, loading or not this keycodes files every time BasiliskII starts is not necessarily the most important point. With your permission, I would rather suggest that there is something to fix somewhere, since BasiliskII doesn't open this file when it is told to do so from its basiliskii.cfg config file.
@AndersHP You mean without emulation? Do you want run the games on your Raspberry Pie or an PC using RetroPie? Games build for PC are usually build for the x86 compatible Intel processors and the Raspberry Pie isn't compatible with them. If you want run PC games on your RPi, then you need to re-encode (means compile or build) for that system. That only works with the source code available and only if someone ports it by changing the code.
If I understood your question wrong, then sorry. Can you clear it up a bit, if I am wrong?
@connormalc Raspbian is just a linux distro with specific Raspberry Pi bits, for x86 hardware I'd install another distro which might be better supported on the PC. PIXEL is the name of the former desktop environment for Raspbian, I don't see how that would help you, maybe you meant NOOBS ?
I'd advise using bootcamp to try out Ubuntu - get the LTS 18.04 version - and install RetroPie on Ubuntu as explained in the Docs.
RetroPie does not run on Windows and while Emulationstation and most of the emulators run also on Windows, it would take some time to manually configure them to work together.
I rebuilt my image using the Attract Mode build and updated everything following Floob's advice. I redid it last night from scratch - and editing the config.tx and cmdline.txt files were successful. I presume I must have missed something or other that caused an issue with the folders. I still need to try Cyberduck, but am now optimistic about being able to SSH.
Hopefully it was just an issue with my install. Thank you for all of the help. Will keep you posted.
The N64 emulator is installed from within the RetroPie-Setup script, not with the procedure you described.
The Errors are logged to ... message is a generic runcommand information message and doesn't mean an error has occurred, but in the event of an error, this is where it would be logged.
RetroPie setup already sets up one of the N64 Emulators ( I think Mupen64 ), so you don't have to install anything, especially macOS binaries that don't run on a RetroPie. Make sure your ROM is valid and try removing any game resolutions you've set, it seems the problem is from your TV not accepting the resolution you set.
@likethereindeer Thanks, but I meant at the beginning of the title so that it reads "[SOLVED] Prep a 128GB Card on Mac". So everyone can see in the topic list that the thread has already been solved. Potential helpers can then look for other problems to solve, and people with the same problem as yours know there may be a solution to be found here. :)