Form ŝīrɛ̄ seems a misprint for šīrɛ̄ judging by the form šīrέh quoted in the context given in [ML 395] and the fact that the word is placed under šrˁ.
Eastern (Dhofari) Mehri. Since post-consonantal ˁ is regularly lost in this Mehri variety, the Central (Eastern Yemeni) Mehri ŝaˁṯáyt is to be considered the direct avatar of the Dhofari ŝāṯáyt. Western (Qishn) Mehri is ŝaγatīt as elicited by A. Jahn (1905:74). W. Hein’s Western Mehri texts feature a number of other variants (Rubin 2018:296), among which ẑaγtīt is the most remarkable one.