Dear Justin,
(a)yaṇaśarakhacare is a chronogram or bhūtasamkhyā, that is the date in the Nepalese era is expressed here by words.
See Richard Salomon, 1998, Indian Epigraphy, p. 173:
"The date of an era may be given in numerical figures, words, or both. In verse
inscriptions, especially from later centuries, it was a common practice to give the
date in the form of a chronogram (bhūtasamkhyā), with the digits expressed by words
for items associated with particular numbers. The suggested numbers are to be read
in reverse order (according to the principle aṅkānāṃ vāmato gatiḥ, "numerals run
leftward") with an understood place value notation; that is to say, the first word in
the chronogram gives the units digit, the second the tens, and so forth."
But see note 31 in R. Salomon: "Occasionally, however, chronograms are intended to be read in normal order".