For locales that are not available for Qt Picard currently shows a warning like:
W: 08:47:12,788 /usr/lib/python3.7/site-packages/picard/tagger.main:861: Error loading Qt locale sv_SE
This actually shows up a lot, since Qt has not that many locales included. If I look at the avilable Qt locales on my system this is only ar, bg, ca, cs, da, de, en, es, fa, fi, fr, gd, gl, he.
But the warning confuses users and makes them think something is broken.
Reduce the log level of this warning and reword it to be less scary.