I tried compiling the multibit version with Phyllis' instructions
(which are also found in the manual:
https://cinelerra-gg.org/download/CinelerraGG_Manual/Multibit_build_x265_8_10_12.html).
With Andrew's new patch "x265-17122023" I have a crash. I attach the
cin5_patch.log.

Without the new patch the build works. I have a Ryzen 5900XT 12c/24t.
I generally compile in just over 3 min. Multibit took a little over 4
min.
NOTE: By applying the "compile_multibit_X265.txt" there is no need to
manually edit ../thirdparty/Makefile, it is done automatically.

I compared the appimage (without new patch) multibit with the build
(without new patch) multibit: I get the same rendering results. The
only difference, as Phyllis had explained, is that in my build the
hevc.mp4 preset also works while in the appimage it does not.