As evidenced in the Player's current translation.cpp code, the game translation guide should not suggest Language/LANGUAGE_NAME/Fonts as a directory, but instead Language/LANGUAGE_NAME/Font to avoid confusing translators.
Thank you for reporting this, it seems to be a typo or a leftover from a development version similar to how the language folder was called languages, will fix it with #93
As evidenced in the Player's current translation.cpp code, the game translation guide should not suggest
Language/LANGUAGE_NAME/Fonts
as a directory, but insteadLanguage/LANGUAGE_NAME/Font
to avoid confusing translators.