There's an array of Region strings, based on the CFG_Region enum from the looks of it, but the code is then calling CFGU_GetSystemLanguage, which will return CFG_Language. So in this users case, their system is probably set to Russian, which returns 10, which is higher than CFG_REGION_TWN (6)
Copy/paste from my issue on FBI, since we use the same code (Albeit lines/files will be different, but that's easy to track down):
Saw someone posted an issue here about 0xD8E3FBFD: https://gbatemp.net/threads/release-fbi-open-source-cia-installer.386433/page-137#post-6402442
Took a look at what FBI was doing in regards to the Seed stuff and just realized it seems to be mixing up Country/Language codes.
https://github.com/Steveice10/FBI/blob/master/source/core/util.c#L275
There's an array of Region strings, based on the CFG_Region enum from the looks of it, but the code is then calling CFGU_GetSystemLanguage, which will return CFG_Language. So in this users case, their system is probably set to Russian, which returns 10, which is higher than CFG_REGION_TWN (6)