A new virtual machine implementation for running IRAF on MacOS 10.14+ is now available. You can find updated instructions at:
This should provide a reliable and relatively convenient way of running Gemini IRAF on recent Apple computers with an M1/M2 processor (though M2 has not been tested yet). However, this comes with an order-of-magnitude speed penalty, because of the need to emulate an Intel CPU on ARM64, which is unavoidable without having 64-bit ports of Gemini IRAF and its dependencies (such as STSDAS). On Apple machines with an Intel CPU, the virtualization overhead is much smaller.