In the Library, each supported language has a specific language code. The language code is used as the name of the subfolders in the Templates folder:
cs: Czech
da: Danish
de: German
en: English
es: Spanish
es-mx: Spanish (Mexico)
fi: Finnish
fr: French
fr-ca: French (Canada)
hu: Hungarian
it: Italian
ja: Japanese
ko: Korean
nl: Dutch
no: Norwegian
pl: Polish
pt: Portuguese
ru: Russian
sv: Swedish
tr: Turkish
zh-CHS: Chinese (Simplified)
zh-CHT: Chinese (Traditional)