I have been using TeXmacs extensively for taking college lecture notes. Then I update my Mac book and it’s a before and after doomsday - TeXmacs does not start up. I have spent 3 hours researching and trouble shooting this error no luck. It might be a new one that is not found before.
Here is the logging report I get in my terminal. There are about ~100 fonts that are approximately transformed. I presume this is not the error, but there were some missing fonts and an error on the libpng.
Mac has a Font Book with all the system fonts. Maybe that changed during the update? But besides these aesthetics I have identified the bug.
eXmacs] approximating font tuple (TwentiethCentury.ttc, 1, 291604) ~> tuple (TwentiethCentury.ttc, 1, 290348)
TeXmacs] approximating font tuple (TwentiethCentury.ttc, 2, 291604) ~> tuple (TwentiethCentury.ttc, 2, 290348)
TeXmacs] approximating font tuple (TwentiethCentury.ttc, 3, 291604) ~> tuple (TwentiethCentury.ttc, 3, 290348)
TeXmacs] With linked TrueType support
TeXmacs] warning, missing font, loading global substitution list
libpng warning: iCCP: known incorrect sRGB profile
zsh: illegal hardware instruction /Applications/TeXmacs.app/Contents/MacOS/TeXmacs
XXXXXXX PROCEEDS TO DIE XXXXXXXXX
Please could some developers help me troubleshoot. I need to urgently retrieve my notes, and I cannot open any .tm files which have all my assignments 
Edit: I am using * Download TeXmacs-2.1.1.dmg for MacOS 10.10 and later.
I just didn’t realize that this bug doesn’t occur to every ARM mac user with an external monitor, until you let me know. No wonder why there’s not so much discussion or solution here. Get quite lost…
Maybe it won’t be figured out and fixed since not many people are having this issue.