ᴱQ. lepsa “liver” appeared in the Qenya Lexicon of the 1910s under the early root ᴱ√LEFE (QL/52). The contemporaneous Gnomish Lexicon had (unglossed) lipsa, in keeping with the revision G. elf >> G. ilf “heart” (GL/50).
Neo-Quenya: I’d retain ᴺQ. lepsa “liver” for purposes of Neo-Quenya.
The word G. rôn⁽⁾ “liver” appeared in the Gnomish Lexicon of the 1910s, but its etymology is unclear (GL/65). Q. rāna “moon” was written in pencil nearby, but this seems to be from an earlier layer of the lexicon, and may be unrelated.
Neo-Sindarin: I’d retain ᴺS. rôn “liver” for purposes of Neo-Sindarin, perhaps as a derivative of the later root √RON “solid, firm”, since (a) there are no later words for “liver” and (b) the word rôn does not appear with any other meaning in later writings.