For some time Qemu now has been supporting gtk and sdl besides the native cocoa display when ran on macOS. I haven 't seen your cocoa error before, so any info you can give might be helpful.
Hi all,
Recently Qemu got the ability to emulate a Quadra 800 capable of running A/UX 3.x. While not yet in the main Qemu source and being considered alpha quality, some ready-to-use builds for Windows and macOS hosts are available at the emaculation forum...