The word ᴱQ. haruni “grandmother” appeared in both the Qenya Lexicon and Poetic and Mythological Words of Eldarissa of the 1910s (QL/39; PME/39). It is a combination of ᴱQ. haru “grandfather” with the female suffix -ni. As there are no other alternatives, I would retain ᴺQ. haruni “grandmother” for purposes of Neo-Quenya.
Early Quenya
haru
noun. grandfather
haruni
noun. grandmother
sorta-
verb. to sit down
A word for “grandfather” of unclear derivation appearing as ᴱQ. haru in both the Qenya Lexicon and Poetic and Mythological Words of Eldarissa of the 1910s (QL/39; PME/39). As there are no other alternatives, I would retain ᴺQ. haru for purposes of Neo-Quenya.