This verb appeared in the Qenya Lexicon of the 1910s with variants ᴱQ. mald- and mild-, both meaning “pound” and derived from the early root ᴱ√MLŘL [MḶÐḶ] (QL/62). Elsewhere in the document Tolkien said the verb mildi- meant “crush, pound” (QL/63).
Neo-Quenya: I would retain this verb as ᴺQ. malda- “to pound”, but update its derivation to be from the later root ᴹ√MBAL (Ety/MBAL).
A word appearing as ᴱQ. mildi “pease” in the Qenya Lexicon of the 1910s derived from primitive ᴱ✶mldẏǝ under the early root ᴱ√MLŘL [MḶÐḶ] (QL/62), where “pease” is an archaic word for “pea”. Tolkien somewhat cryptically said it was “used plural or as yə sing”. I interpret this to mean that it could be used as a collective plural form, or as a singular with stem mildy-. Tolkien could have been indicating that its singular ✱milde was a back formation from its apparently plural form mildi, much how English “pea” was derived from apparently plural “pease”, originally from Latin “pisa”.
Neo-Quenya: I would adapt this word as ᴺQ. mildë (mildi-) “pea” for purposes of Neo-Quenya.