As I mentioned in https://debbugs.gnu.org/cgi/bugreport.cgi?bug=36284#8,
a proper fix would be to implement replacements for
XftDefaultSubstitute and XftDefaultSet.
How complicate will such a change be? Will it be simple and safe
enough to allow installing such a change on the emacs-27 branch?
Ping! Could we please try solving this for Emacs 27.2? Mitsuharu,
could you please show the fix you had in mind back then?
Hey! Is there any news around this? The XFT backend seems to have some
issues with TTC fonts that the Cairo backend does not.
Sadly, no news yet. Patches or ideas how to fix this are welcome.
I'll try to do something, but I have no experience with either Xft or
Cairo, so if that's something clever to do, I am likely to fail.