In the Quenya Verbal System (QVS) of the late 1940s, Tolkien described a “long perfect” that developed along the same lines as the Quenya pluperfect (past perfect):

A weak “pluperfect” was made in Quenya, by adding to the perfect participle the past-suffix -nḗ. So karnelyane “I was having made = I had made”; túlielyane “I had come”, lasselyane “I had heard”, etc.

See further under weak verbs. Since these could not normally distinguish between past and perfect [sidenote: sc. when they had no strong pa.t.] their perfect was periphrastic: thus ni nahtanelya “I (am) having slain” = “I have slain”; but also where no pronoun was concerned Orome nahtanelya “O. has slain”. From the latter developed the form nahtanelye or by analogy with the strong verbs anahtalye “has slain”. The final vowel -e is on analogy of the normal perfect ending.

In verse, where convenient, similar forms were made from strong verbs: akárielye/akarnelye = akárie. But there is frequently a slight difference of sense, the longer form being more nearly equivalent to English “I have been making”. These are called “long perfects” (QVS, PE22/104).

The net effect of all of the above is that derived verbs (especially weak verbs and causatives) in QVS frequently used -lye or -nelye to form their perfects rather than -ie:

• ᴹQ. ampanóta- “build” → long perfect ampanotelye (PE22/118).
• ᴹQ. ehtelu- “bubble up” → long perfect ehtelunelye vs. simple perfect etekélie (PE22/103).
• ᴹQ. ninqita- “whiten” → long perfect niñkwitanelye vs. weak perfect (i)niñqitanie (PE22/117).
• ᴹQ. ninqinta- “become white” → long perfect niñqintantelye (PE22/117).
• ᴹQ. orta- “raise” → long perfect ortanelye vs. weak perfect ortanie (PE22/117).

The origin of the “long perfect” is rather convoluted. In QVS, Quenya had a complex system of compound tenses produced by combining various grammatical endings (see compound tenses for further details). In this document, Quenya had a suffix -lya that Tolkien labeled the imperfect participle, that “denoted (more or less) continuous action contemporary with that of the main verb” (PE22/107). It was added to the verb stem: karalya “doing, making”; tululya “coming”. The same suffix was used to produce a “perfect participle”, added to either the past or perfect verb form: karnelya “having done”; †tullelya, utúlielya “having come”. These “normally refer to an action that has been (or was) completed before the main action” (PE22/108).

These perfect participles could be used to form a periphrastic (that is, indirect) perfect tense as in i nér (yé) karnelya “the man (is) having done [it] = has done [it]” (in QVS, yé was the verb for “to be”). In derived verbs, these periphrastic expressions became the norm: i nér (yé) ortanelya “the man (is) having raised [it]”. The perfect participle then developed into a verb form, with the final a becoming e by analogy with the normal past/perfect: karnelye, ortanelye. It seems that in exceptionally long verbs, this new perfect suffix -nelye could reduce to -lye: ampanotelye.

Neo-Quenya: It is unlikely that the long perfect remained valid in Quenya as Tolkien conceived of it in the 1950s and 60s. I would not use this construction in Neo-Quenya, sticking with the ordinary perfect instead.