After you have added a new language in the Fresns admin panel, you need to fill in the values for that new language in all multilingual configuration items.

Otherwise, if you use that language on the client side, the client side display will be empty because its value is empty.

Systems→General (Site Name, Site Intro)
Systems→Policy→Contents (Terms, Privacy, Cookies, Delete Account)
Systems→Wallet→Options (Currency Name, Currency Unit)
Systems→Wallet→Recharge Services (Name of the items)
Systems→Wallet→Withdraw Services (Name of the items)

Systems→Operations→Rename (All)
Systems→Operations→Stickers (Group Name)
Systems→Operations→Roles (Name)
Systems→Operations→Groups (Name, Description)

Systems→Extends→Content Type (Name)
Systems→Extends→Editor (Name)
Systems→Extends→Manage (Name)
Systems→Extends→Group (Name)
Systems→Extends→User Feature (Name)
Systems→Extends→User Profile (Name)
Systems→Extends→Channel (Name)

Systems→Clients→Menus (All)
Systems→Clients→Columns (All)
Systems→Clients→Language Packs (New Language)
Systems→Clients→Code Messages (New Language)