The transliteration rules will be implemented in the new Balinese LanguageConverter class (under review). However, the existing LanguageConverter facilities are not sufficient, because I don't want to convert whole pages into either Balinese or Latin script. Rather, I want the Latin transliteration to supplement the Balinese original and appear below it. This means that I need a way to convert particular chunks of wikitext from one Balinese variant to another, and insert the result in a flexible manner.
To do this, I propose adding a <langconvert> tag to CoreParserTags.php to allow flexible access to LanguageConverter. It takes two attributes: from (language variant from) and to (language variant to). For example, <langconvert from="sr-el" to="sr-ec">zdravo</langconvert> would return "здраво" (Latin Serbian to Cyrillic Serbian).