I would like to work with Jorge Lopez-Nava [wikis.swarthmore.edu/ling073/User:jlopezn1].
ISO 639-3: tsz
Purépecha is currently spoken in the highlands of Michoacán, Mexico.  There are approximately 55,000 speakers of the language in all countries.  It's considered a language isolate, meaning that it doesn't seem to be related to any other known languages.  It's also considered an agglutinative language, but is sometimes considered polysynthetic as well.  Its current AES status is shifting ; similarly, its language status is 5 (Developing).  It uses Latin script , but the official alphabet is the P’URHEPECHA JIMBO KARARAKUECHA (Purépecha Alphabet). 
There seem to be various sources available (on Glottolog).
ISO 639-3: tnl
Lenakel is spoken on the western coast of Tanna Island in Vanuatu by approximately between 8,500 to 11,500 speakers. Its language status is 5 (Developing).  It also uses Latin script . No further information was found at the moment.
Linguist John Lynch has done extensive research and documentation of Lenakel, so I think there will be various sources available.
ISO 639-3: jje
Jeju has 5,000 speakers in South Korea. It's a head-final, agglutinative, suffixing language. It historically does not have a writing system, but there are two recently devised orthographies in use. Both versions use the Korean alphabet Hangul along with one additional letter ㆍ, a character previously used in the Middle and Early Modern Korean scripts. There are two orthographies largely based on the differing morphological analyses analyses of the language.  Its language status is 8a (Moribund). 
There doesn't seem to be too much, but revitalization efforts are ongoing.