HTML Errors in Create, Edit, Translate pages

Syntax of language tag:
    An RFC 5646 language tag consists of hyphen-separated ASCII-alphanumeric subtags. There is a primary tag identifying a natural language by its shortest ISO 639 language code (e.g. en for English) and zero or more additional subtags adding precision. The most common additional subtag type is a region subtag which most commonly is a two-letter ISO 3166 country code (e.g. GB for the United Kingdom). IANA maintains a registry of permissible subtags. 

    Line 136, column 74: Bad value Arabic for attribute lang on element a: The language subtag arabic is not a valid IANA language part of a language tag.

    …           <li><a class="language-item" href="#" lang="Arabic">العربية</a></li>

    Line 138, column 75: Bad value Chinese for attribute lang on element a: The language subtag chinese is not a valid IANA language part of a language tag.

    …               <li><a class="language-item" href="#" lang="Chinese">中文</a></li>

    Line 140, column 73: Bad value Dutch for attribute lang on element a: The language subtag dutch is not a valid IANA language part of a language tag.

    …         <li><a class="language-item" href="#" lang="Dutch">Nederlands</a></li>

    Line 142, column 75: Bad value English for attribute lang on element a: The language subtag english is not a valid IANA language part of a language tag.

    …          <li><a class="language-item" href="#" lang="English">English</a></li>

    Line 144, column 74: Bad value French for attribute lang on element a: The language subtag french is not a valid IANA language part of a language tag.

    …          <li><a class="language-item" href="#" lang="French">Français</a></li>

    Line 146, column 74: Bad value German for attribute lang on element a: The language subtag german is not a valid IANA language part of a language tag.

    …           <li><a class="language-item" href="#" lang="German">Deutsch</a></li>

    Line 148, column 73: Bad value Hindi for attribute lang on element a: The language subtag hindi is not a valid IANA language part of a language tag.

    …              <li><a class="language-item" href="#" lang="Hindi">हिंदी</a></li>

    Line 150, column 75: Bad value Italian for attribute lang on element a: The language subtag italian is not a valid IANA language part of a language tag.

    …         <li><a class="language-item" href="#" lang="Italian">Italiano</a></li>

    Line 152, column 76: Bad value Japanese for attribute lang on element a: The language subtag japanese is not a valid IANA language part of a language tag.

    …             <li><a class="language-item" href="#" lang="Japanese">日本語</a></li>

    Line 154, column 74: Bad value Korean for attribute lang on element a: The language subtag korean is not a valid IANA language part of a language tag.

    …               <li><a class="language-item" href="#" lang="Korean">한국어</a></li>

    Line 156, column 74: Bad value Polish for attribute lang on element a: The language subtag polish is not a valid IANA language part of a language tag.

    …            <li><a class="language-item" href="#" lang="Polish">Polski</a></li>

    Line 158, column 78: Bad value Portuguese for attribute lang on element a: Subtags must not exceed 8 characters in length.

    …     <li><a class="language-item" href="#" lang="Portuguese">Português</a></li>

    Line 160, column 75: Bad value Russian for attribute lang on element a: The language subtag russian is not a valid IANA language part of a language tag.

    …          <li><a class="language-item" href="#" lang="Russian">Русский</a></li>

    Line 162, column 75: Bad value Spanish for attribute lang on element a: The language subtag spanish is not a valid IANA language part of a language tag.

    …          <li><a class="language-item" href="#" lang="Spanish">Español</a></li>

    Line 164, column 75: Bad value Turkish for attribute lang on element a: The language subtag turkish is not a valid IANA language part of a language tag.

    …           <li><a class="language-item" href="#" lang="Turkish">Türkçe</a></li>

    Line 166, column 77: Bad value Ukrainian for attribute lang on element a: Subtags must not exceed 8 characters in length.

    …     <li><a class="language-item" href="#" lang="Ukrainian">Українська</a></li>