Inconsistent CJK font display [solved]

[superjaded]

I have a new installation of gentoo and everything seems to be coming together except for CJK support. This doesn't usually seem to be something I have to worry about as long as I have the appropriate fonts installed these days, so I'm at a loss with regards to what I'm missing. Non-latin characters seem to display fine in GTK (or at least Firefox) and mpv, but they do not show up properly in Qt (I'm using KDE) or rxvt-unicode.

Perhaps somewhat amusingly, I say Qt apps don't display CJK properly, but the titlebar seems to render non-latin characters properly, as illustrated by the mpv screenshot. Something that the mpv screenshot doesn't show properly is that the OSD (which displays the filename/title of the video being played) displays properly.

I initially just installed the noto-cjk fontset. When I was still having issues with non-latin characters, I eventually remembered the cjk USE flag, which didn't actually affect many packages. I also eventually installed/enabled IBus. I also installed the fonts referenced in the How to read and write in Japanese wiki page.Nothing seemed to resolve the display issues.

One other observation, I can use IBus-Anthy to write Japanese characters in Kate, but I can't write Japanese characters in rxvt-unicode (which has worked in the past, at least in different gentoo installations).

Here are some examples of how the same directory looks in different apps.

Some config files:

• /etc/fonts/local.conf - only real fontconfig related change I've made. Makes default Sans and Serif font Cantarell and default Monospace font Hack. I know this isn't (directly) the issue since I've used it in multiple installs without this behavior. I also removed local.conf in my testing and didn't change the display behavior.
  
• /etc/portage/make.conf
  
• /etc/portage/package.use/*
  

Any help would be appreciated. I have a feeling based off past experience I'm going to feel real dumb when I find the resolution.

EDIT:

Not sure if it was actually what I did, but things seem to be working properly now. Turns out I never set my locale, so I set that to en_US.utf8.

I also ran an update earlier this afternoon which seemed to be the point after which things started working. If nothing else, harfbuzz had an update. I rebooted and now non-latin characters are displaying properly.