tldr, change FC_SCALABLE in x.c from 1 to 0. (comes from the font2 patch)
For some context, I have been using xterm for a long while when I’m on OpenBSD since it is included by default in Xenocara with Terminus as my default font, and the main reason why I did not use st again was that my bitmap fallback font for CJK was not loading. Instead, I get an ugly sans-serif scaled font that looked very out of place in my otherwise clean and crisp bitmap terminal.
Yes, I did make sure that the font2 patch for st was applied correctly.
The X11 font string for reference is Fixed:
-misc-fixed-medium-r-normal-ja-18-120-100-100-c-180-iso10646-1
It also didn’t help that fontconfig was unable to find the font either no
matter how much I looked for it with fc-list and fc-match. The weirder thing is
that when I installed GNU Unifont to my fonts directory, fontconfig was able to
find it and st loaded it (I put a printf in the xloadfonts() function in x.c),
but the same old ugly scaled font was still being shown for CJK. The weirderer
thing was that Unifont was rendering just fine when being used as the main font
instead of in font2.
I thought to myself why this was happening and wasn’t able to find out, until I
reread the font loading portion in x.c’s xloadsparefonts() function that came
part of the font2 patch.
It had set the FC_SCALABLE boolean to 1 (true). That explained why the fallback
font rendered fine as the main font and not fallback. Setting that boolean to
0 (false) fixed my fallback font not matching issue, and now I have clean and
crisp looking text that I can read more easily.
I already disliked fontconfig, freetype, xft, and friends (don’t get me started on pango and harfbuzz), but this incident made me dislike it further.