Nahman Avigad discusses stamps that attests to יאש (Ya'ush) being a Semitic name.
Nahman Avigad, Corpus of West Semitic Stamp Seals, ed. Benjamin Sass, revised ed. (Jerusalem: The Israel Academy of Sciences and Humanities, 1997), 184, 202-3
לאלנתן Belonging to Elnatan
בן יאש son of Ya'ush
Jerusalem, Y. Sasson collection.
Impression 12 x 9 mm.
. . .
ליאש בן Belonging to Ya'ush son of
אלשמע Elishama
(A) Jerusalem, Y. Sasson collection (A 66); (b) Antwerp, Ch. Kaufman collection; (c) Lonson, S. Moussaieff collection.
Three impressions, 11 x 9 mm, bezel groove.
Single(?)-line border, double-line field divider, two inscribed registers.
ליאש Belonging to Ya'ush
[ב]ן פדיהו [so]n of Pedayahu
Jerusalem, Y. Sasson collection.
Impression c. 11.5 x 11.5 mm.
Single(?)-line border, double-line field divider, two inscribed registers.