A verb appearing in the Gnomish Lexicon of the 1910s as G. gwil- “sail, float, fly” derived from ᴱ√gu̯il (GL/45). It was cognate to ᴱQ. vil- or ’wili- “sail, fly, float” (QL/104).
Neo-Sindarin: Since [ᴹQ.] vil- or wil- “fly” survived in Tolkien’s later writings (Ety/WIL), I would retain ᴺS. gwil- as well, but only for the sense “to fly”. For “float” and “sail” I would use other verbs like ᴺS. loda- “float” [N. lhoda-] and ᴺS. renia- “sail” [N. rhenia-].
A word appearing in the Gnomish Lexicon of the 1910s as G. gwailtha- “to air - expose to air”, a verb form of G. gwail “air” from the root ᴱ√gu̯il (GL/45).
Neo-Sindarin: I think this word can be salvaged as a causative verb ᴺS. gwiltha- of the same meaning, from the later version of its root: ᴹ√WIL which still have derivatives related to “air”, such as N. gwelw “air (as a substance)” (Ety/WIL).