Syr. ܡܵܐܐ‏, pl.: ܡܲܐܘ̈ܵܬܵܐ‏; JLA pl. מַאְַוָתָא ; dual: see s.v. mˀtyn num. ; after a preceding numeral (i.e. 400), the singular form is regularly used, hence in Syriac and Mandaic orthography often joined as a single word to previous cardinal, for which see s.v. e.g. tltmˀh; Qum. pl. possibly מא]ין ; Sam. pl. מון

The singular form is used both with plural nouns and with collectives.
In the cited JBAmb passage for "unit of a hundred", the demon named אני has the epithet "river" in other related texts, so we must keep a meaning "her water" as an option for the form מוה, and so we have parsed it in the text module.