Use part1 instead of part3 language codes

cps/kobo.py

@@ -45,6 +45,7 @@ import requests
 
 
 from . import config, logger, kobo_auth, db, calibre_db, helper, shelf as shelf_lib, ub, csrf, kobo_sync_status
+from . import isoLanguages
 from .constants import sqlalchemy_version2, COVER_THUMBNAIL_SMALL
 from .helper import get_download_link
 from .services import SyncToken as SyncToken
@@ -446,7 +447,7 @@ def get_seriesindex(book):
 def get_language(book):
     if not book.languages:
         return 'en'
-    return book.languages[0].lang_code
+    return isoLanguages.get(part3=book.languages[0].lang_code).part1
 
 
 def get_metadata(book):