At FTV Num24:6 בכריותיה is a mistake for בבריותה as in the other Palestinian versions. See s.v. bryw.
Although Ishodad connects the semantics of "stream" and "grief" in the first cited passage, his unique use of this word in the former sense is probably to be connected rather with kry vb. : to dig, to bore, otherwise unattested in Syriac.