A noun appearing as G. ceral “jar” in Gnomish Lexicon Slips of the 1910s from primitive ᴱ✶keréldǝ (PE13/116). It is likely based on the early root ᴱ√KERE “turn” (QL/46).
Neo-Sindarin: A similar root √KWER “revolve” appears in Tolkien’s later writing, so I would adapt this noun as ᴺS. perol “jar” from ancient ✱kwerḷ.
A word appearing as G. ulm “jar, flagon” in the Gnomish Lexicon of the 1910s derived from ᴱ✶ḷm (GL/74). In the contemporaneous Qenya Lexicon Tolkien said it was not related to the early root ᴱ√ULU “pour” because Gnomish derivatives of that root showed gul- indicating a true root form ✱ᴱ√GULU (QL/97). Tolkien soon changed his mind and decided the root for “pour” was in fact ᴱ√ULU, and the primitive form ᴱ✶ḷm was deleted from the Gnomish Lexicon.
Neo-Sindarin: I would retain this word for purposes of Neo-Sindarin, but would assume it was derived from ✱ul-mā “a thing for pouring”. As such, I would assume its use included pitchers with handles as well as flagons and jars. Its form would need to be adapted as ᴺS. olf to fit Sindarin phonetics, with u becoming o before a and then [[s|lm > lf (pronounced [lv])]].