I have developed for the Blackfin before (bootloader, kernel, and app development) and used Ubuntu (Xenial), but that was for a client who provided the PC hardware to host Ubuntu. If I can get started on Aleph, I would want to host the tools on Mac.
It is possible to have a case sensitive filesystem on macOS, but you probably need a second partition so that the boot drive can be standard mac insensitive. I have an old cvs repository that I needed to host on my new mac mini, and found that it also needs a case sensitive filesystem. I simply created a spare 100 GB partition and formatted it with Mac OS Extended (Case-sensitive, Journaled). I now place projects on that drive when needed.
I realize that this thread is eighteen months old, but I just got here.