Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
cwil
noun. hue, tint
cwîl
adjective. quiet, peaceful, gentle
cwildred
noun. bat (animal)
A word appearing as G. cwildred “bat (animal)” in the Gnomish Lexicon of the 1910s, an (agental?) elaboration of G. cwîl “quiet” (GL/28). According to the editors, the first d was circled, perhaps indicating it was optional or lost (cwilred).
Neo-Sindarin: For purposes of Neo-Sindarin, I would revise this word to ᴺS. pillor as an agental form of the Neo-Root ᴺ√KWILID.
cwiliog
adjective. bright-hued
cwileg
noun. alder
A word for “alder” [a type of birch tree] in the Gnomish Lexicon of the 1910s, apparently based on G. cwîl “quiet” (GL/28).
cwilon
adjective. bright-hued
An adjective appearing as G. {cwild >>} cwîl “quiet, peaceful, gentle” in the Gnomish Lexicon of the 1910s (GL/28). It is clearly related to ᴱQ. qilda “quiet, hushed, still” based on the early root ᴱ√QḶŘḶ [QḶÐḶ] (QL/78).
Neo-Sindarin: For purposes of Neo-Sindarin I would adapt this word as ᴺS. pell fitting the Sindarin phonetic developments from primitive ✱kwildā as originally suggested by Fiona Jallings, but Fiona gave it the same gloss as its Early Qenya equivalent, whereas I would use the glosses “quiet, peaceful, gentle” from Gnomish.