A noun appearing as G. bothli “oven” in the Gnomish Lexicon of the 1910s, derived from primitive ᴱ✶mᵇāsḷ (GL/23) and thus based on the early root ᴱ√M(B)ASA “cook, bake” (QL/63).
Neo-Sindarin: Since √MBAS “bake” continued to appear in Tolkien’s later writings, I would retain this word but adapt it as ᴺS. bothol “oven” to better fit later Sindarin phonology: [mbāslǝ] > [mbǭsḷ] > [mbauθḷ] > [boθol]. Here final syllabic ḷ became -ol, as in tachol < ✶tankl(a) (PE18/100).
The verb G. {urtha- >>} urna- “blaze, burn (intr.)” appeared in the Gnomish Lexicon of the 1910s (GL/75), probably derived from the early root ᴱ√URU which had several fire-related derivatives (QL/98).
Neo-Sindarin: For purposes of Neo-Sindarin, I think this verb can be adapted as ᴺS. orna- from the later root √UR, and it can be used for “burn” in general (both transitive and intransitive) since the other transitive Gnomish “burn” words like G. gusta- cannot be easily adapted.