Namkung, Ju. Phonological Inventories of Tibeto-Burman Languages. 1996. hh:hld:Namkung:Tibeto-Burman
ui |
naaa1245 isn't listed in the Glottolog entry for this source, but seems to be the best candidate for the identity of Bengni -- it has a dialect called Bangni (an alternate spelling for Bengni in JS-HCST) and it appears to be spoken in the right place.
"Short vowels [in open syllables] carry a final consonant at the phonetic level, which varies between [-k], [-ʔ], and a fricative. Thus, the word for 'tooth' /fi/ is realized as [fik], [fiʔ], or [fiç]." It's unclear what the fricative is for other values, but here we assume it's [x].
Tone may marginally exist.