What is the correct interpretation of these verse from kaushitaki upanishad?

Question

3. He going by the path by which the immortal gods travel reaches the world of Agni (fire), then to the world of Vayu (air), then to the world of Varuna, then to the world of Aditya (sun), then to the world of Indra, then to the world of Prajapati, then to the world of Brahma. In this world of Brahma, verily, is the lake Ara, points of time called Yestiha, the river Viraja, the tree Ilya, the city Salajya, the court of Aparajita, the door keepers Indra and Prajapati, the hall Vibhu, the throne Vicaksana, the couch Amitaujas, the beloved Manasi and her twin Caksusi weaving the worlds with flowers, Ambas (mothers), Ambavayis (nurses), Apsaras (celestial beauties), and the rivers called Ambayas. To this world comes the knower of this. To him Brahma says, "Welcome, you have my glory and you have reached the ageless river Viraja and you will never age."

From chapter 1 verse 3

4. Five hundred Apsaras (heavenly beauties) come to him from the other side, one hundred holding fruits in their hands, a hundred with ointments in their hands, a hundred bearing perfumes in their hands, one hundred with garments in their hands, and one hundred with powder in their hands. Then they adorn him just like the way Brahma is adorned. Then, with the adornments of Brahma, goes the knower of Brahma into (the world of ) Brahma. He comes to the lake Ara and crosses it with his mind, coming to which others who know only the present (world) sink. He reaches the points of time called Yestiha and they flee from him. He comes to the lake Viraja and crosses it with his mind. There he washes away his both good and evil deeds. Of those deeds, his beloved ones receive the results of good deeds and his and his unpleasant relations receive the results of bad deeds. Thus just as a man in a chariot looks at the two wheels so does he look at the day and night, at good deeds and bad deeds and all dualities. thus leaving behind both good deeds and bad deeds, the knower of Brahman goes towards Brahman.

Chapter 1 verse 4

Are these verse say about eternal heaven.

Answer 1

The answer is given in the first line of the verse 1.3: 'then to the world of Brahma'. The verses are describing the path to Brahma-loka followed by people who follow the path of krama-mukti (gradual liberation). Note the last line of the second verse which says 'the knower of Brahman goes towards Brahman'.

Those who have the Advaita experience here do not have to go anywhere and become Brahman while living (jivanmukta).

Brahma-loka is hiranya-garbha-loka of which an account is given.

The lake ara is the first impediment to entrance into brahma-loka. It is said to be composed of the enemies (desire, wrath).

The Principal Upanishads by S. Radhakrishnan.