■■1. Yes, Ramayana or Mahabharata may repeat in many kalpas and chaturyugas..
Read Yog Vasistha there Kak Bhusundi says he had seen Ramayan 11 times and Mahabharat (Krishna) 16 times with different outcomes...
Yogvasistha chapter 21
I remember Lord Vishnu descending many times on earth to destroy ferocious rakshasa demons, and
is now to appear here the eleventh time under the name of Rama.
I know Lord Hari (Vishnu) has
come down three times in his form of the half lion half man Narasimha to thrash the demon
Hiranyakashipu as many times like a lion killing an elephant.
Vishnu is yet to be born in his
sixteenth incarnation at Vasudeva’s abode for the purpose of rescuing the earth from the burden of the
oppression of its tyrant lords and despots. "
Tulsidas in Ramcharitmanas also says Ramayan happened many times in this and other universes...The cause may be different in different kalpas and chaturyuga... One time Ram manifested to make curse of Jalandhars wife ( may your wife be abducted by other and may her purity be questioned by other) come true... Another time Narad cursed Vishnu to be dependent on monkeys as he had made him look like monkey (Hari mukh), for this he incarnated... Another time he incarnated to liberate his eternal servant Jay and Vijaya born as Ravana and Kumbhakarna... Another time to liberate two kings born as Ravana and Kumbhakarna... Another time Bhrigu cursed Vishnu to suffer wife loss... Sometime without cause in leela form... Sometime as boon to Manu and Shatrupa and soo on.....some event coincide here also..
source Bal kanda and Uttar kanda of Ramcharitmanas and Vishnu puran Shiva puran and other
■■2. Ramayan is likely to place in 24th Treta of a kalpa.. But as God is beyond space and time it has nothing to do with specific number... But if not taken place after 24th Treta in this kalpa it still means immortality of Hanuman... Because the recent Mahabharat was in 28th Dwapar yuga where there was Hanuman( met Bhima lord Krishna and sat on chariot flag of Arjun) and we are in 28th Kali yuga...Ramayan may also have happened in current chaturyuga and its information may have been absent ( as devta referring to the period they have told in Puran may be of any kalpa they had seen)
Treta yuge chaturvinshe ravane tapseh shakshyat |
Ram dashrtathi prapiye sagane shakyamiyeewan ||
[Vayu Puraan 70.88]
Chaturvinshe yuge chapi vishwamitra pure sare |
Loke ram iti khyate tejsah bhaskaropam ||
Chaturvinshe yuge vats tretayaam raghuvanshaje |
Ramo naam bhavishyami chaturvhayu sanatane ||
[Brahmand Puraan 18.104.22.168]
■■3. Information may have been lost due to delusion potency of Kali and Shri Hari. Also many original scriptures are lost by influence of Kali.. ( from description of Kali age in various Purans ) stating due to Kali original scripture and interpretations are lost..
for eg. Buddha also told even Vedas are altered in his period...
In the Buddhist Vinaya Pitaka of the Mahavagga (I.245) section the Buddha names these rishis. The names of the Vedic rishis were "Atthako, Vâmako, Vâmadevo, Vessâmitto, Yamataggi, Angiraso, Bhâradvâjo, Vâsettho, Kassapo, and Bhagu" but that it was altered by a few Brahmins who introduced animal
sacrifices. The Vinaya Pitaka's section Anguttara Nikaya: Panchaka Nipata says that it was on this alteration of the true Veda that the Buddha refused to pay respect to the Vedas of his time. >
(( This is only for information as Vedic student can defend this statement referring Buddhism as belonging to Nastika school ))
Also many chaturyuga can go waste without anything... Kakbhusundi in Maharamayan tells Vasistha that there were yugas he saw where there were no mountains , no people etc...
Chapter 21 Maharamayan
I remember seeing no other creature on earth except plants for the long duration of half of the four yuga
I also remember this earth full of mountains for the space of four full yugas when there wereno men on earth and their customs and usages had no ground in it.
I remember seeing this earth filled with the bones of dead Daityas and other fossil remains rising in
heaps like mountains and continuing in their dilapidated and crumbling state for myriads of years
■■4. Prajapati Daksha also appeared many times in different kalpa and yuga and universes. In Yogvasistha Bhusundi tells he went to see Daksh yagya twice but as the result were same in both time he didnt went to see from next time..
(source chapter 21 of Maharamayan)
Also in tantra Mahadev being asked by Parvati about skull he was wearing he tells it was her skull in previous yugas and creations. And so events are repeatef source aagam doctrines
■■5. It is so because same story happens by a little bit different way when it is repeated in yugas and kalpas... The story are of different time lines... for eg. See the way of birth of Vasistha in different yugas..
Chapter 21 Maharamayan
O sagely son of Brahma, I remember your eight births in the eight different epochs of the world. This
is your eighth birth in which you have come as a guest to my nest.
9 At one time you were born of air,
and at another of heavenly fire. One time you were produced from water, and at others from emptiness
and of solid rock.