An adjective appearing as ᴱQ. kalaina or kalainea “serene” in the Qenya Lexicon of the 1910s under the early root ᴱ√KALA “shine golden” (QL/44). Kalaina also appeared in the contemporaneous Gnomish Lexicon as equivalent to G. glaim “serene, clear, fair (espec. of weather)” (GL/39), so it may originally have referred to clear weather.
Neo-Quenya: Since √KAL still referred to “light” in Tolkien’s later writings, I would retain ᴺQ. calaina “serene” for purposes of Neo-Quenya.
A noun appearing as ᴱQ. kalaine “serenity, serene (n.)” in the Qenya Lexicon of the 1910s under the early root ᴱ√KALA “shine golden”, a noun form of adjective kalain(e)a “serene” (QL/44).
Neo-Quenya: I retain the adjective ᴺQ. calaina “serene” for purposes of Neo-Quenya, so I would retain noun ᴺQ. calainë “serenity” as well.