-r plural ending used on verbs with a plural subject (VT49:48, 50, 51), e.g. lantar "fall" in Namárië (with the plural subject lassi "leaves"), or unduláver as the pl. form of undulávë "licked down, covered" (PE17:72). The ending is sometimes missing where we might expect it; for instance, the verb tarnë "stood" has multiple subjects and yet does not appear as *tarner in PE17:71.
Quenya
tar-
verb. to stand
lantar
fall
tar-
stand
#tar- (3) vb. "stand", attested in the past tense: tarnë (PE17:71)
lanta
fall
lanta (1) noun "a fall" (DAT/DANT (TALÁT) ), also lantë.
lanta-
fall
lanta- (2) "fall" (DAT/DANT (TALÁT), Narqelion, VT45:26, VT49:54); lantar aorist tense pl. (Nam, RGEO:66); pl. pa.t. lantaner "fell" (pl.) (SD:246); lantier "they fell", a plural past tense of lanta- "fall" occurring in LR:47; read probably lantaner in LotR-style Quenya, as in SD:246. Also sg. lantië "fell" (LR:56); read likewise *lantanë? (The forms in -ier, -ië seem to be properly perfects.) Future tense lantuva, VT49:47. Participle lantala "falling" (with locative ending: lantalassë) in Markirya.
lantë
fall
#lantë (1) noun "fall" in Noldolantë, q.v. Also lanta.
termar-
stand
termar- vb. "stand" meaning last (ter-mar- "through-abide"); future tense termaruva in CO.
lantë
noun. fall
A noun for “fall” appearing as an element of the title Noldolantë “Fall of the Noldor” (S/87).
Neo-Quenya: The word lasse-lanta “leaf-fall” (LotR/1107) indicates the noun for “a fall” should be lanta, which is also how the noun appears in The Etymologies of the 1930s (Ety/DAT). However, there is an alternate form lassewinta “leaf fall” in drafts of the Lord of the Rings appendices (PM/376) where the second element seems to be the infinitive of the verb winta-, so perhaps lasselanta also includes the infinitive of the verb lanta- “to fall”.
The form lantë more strongly resembles other Quenya nouns, which more often end in -e rather than -a. As such, I prefer lantë over lanta as the independent noun for “a fall”.
tyul-
verb. to stand
A neologism coined by Alex Grigny de Castro in PPQ (PPQ) from the early 2000s, based on the root ᴹ√TYUL “stand up (straight)”, along with an intransitive variant ᴺQ. tyulya- and a transitive form ᴺQ. tyulta- (inspired by ᴱQ. tyulta-) suggested by Helge Fauskanger. I’d stick to attested tar- instead for “stand (intr.)”, which was published in 2007.
The root √TAR is translated “stand” in notes from around 1967 (PE17/186), and its past form tarne “stood” appears in a sentence from the same document: sanome tarne Olórin, Aracorno... “there stood Gandalf, Aragorn...” (PE17/71).
Conceptual Development: Early Qenya Word-lists of the 1920s had ᴱQ. hyā- “stand” (PE16/132). The Quenya Verbal System (QVS) of 1948 had a past form ᴹQ. tolle “stood” (PE22/117) and an inceptive verb ᴹQ. tolu- “stand up” (PE22/114) clearly based on ᴹ√TOL (Ety/TOL²), but later in the same document had ᴹQ. thar- “stand” based on the root ᴹ√THAR (PE22/126), probably a precursor to later tar- “stand” < √TAR.