A verb appearing as ᴱQ. silt- “sort out, sift, winnow” in the Qenya Lexicon of the 1910s based on the early root ᴱ√SḶTḶ (QL/84). The verb form silte reappeared in the Early Qenya Grammar (EQG) of the 1920s derived from primitive ᴱ✶sḷt- “sift” (PE14/58).
Neo-Sindarin: I would adapt this verb as ᴺQ. silta- “to sift, sort out, winnow” based on a neo-root ᴺ√SILIT.
A noun appearing as ᴱQ. silta “sieve” in the Qenya Lexicon of the 1910s based on the early root ᴱ√SḶTḶ (QL/84). In very light pencil Tolkien add (ṇ) after it, perhaps considering a change in the root.
Neo-Sindarin: I would retain this noun as ᴺQ. silta “sieve” based on a neo-root ᴺ√SILIT.