The Greek that is translated in English as “daughter” is translated in Lamba as “(non-gendered) child,” wemwana wanji. This is the idiomatic way of referring to children and while it’s possible to specify “female child,” it was felt to be unidiomatic and therefore to be avoided. (Source C. M. Doke in The Bible Translator 1958, p. 57ff.)
See also son.