Aside from needing a way to specify multilingual names, we may also want to enter transliterations. As there doesn't appear to be a standard of codes for transliterations, this page should list the codes that are being used.
For Chinese, the following have been proposed:
zh_py=<Chinese pinyin (toneless)>
zh_pyt=<Chinese pinyin (with tones)>
However, from the Multilingual names page, and in practice, it seems the convention is:
name:en=<Chinese pinyin (toneless and with some basic words translated)>
name:zh_pinyin=<Chinese pinyin (with tones)>
Arabic is commonly transliterated using wikipedia:DIN_31635.
ar_din=<Arabic DIN 31635>
For Japanese, common romanization systems are Hepburn romanization, Kunrei-shiki Rōmaji (ISO 3602) and Nihon-shiki Rōmaji (ISO 3602 Strict). The Hepburn romanization is the most common one (eg, used in Wikipedia  and Wikivoyage), and therefore the recommended one.
ja_rm=<romanization of Japanese>
The Kannada language is transliterated using the standard ISO 15919. See name:kn:iso15919=* for more details.