Dr. Neale's rendering of the lines 25-30 is:—
Jerusalem luminosa. [Eternal Life.] This hymn, in 100 lines, was first published by Mone, No. 304, from a 15th century manuscript at Karlsruhe, in which it is entitled, "On the glory of the heavenly Jerusalem as concerning the endowments of the glorified body." Of this and the two cognate hymns of this manuscript ("Quisquis valet" and "In domo Patris," q.v.) Dr. Neale says, “The language and general ideas prove the writer [unknown, but apparently of the 15th century] to have been subject to the influence of the school of Geert Groot and Thomas à Kempis "(Hymns chiefly Mediaeval on the Joys and Glories of Paradise, 1865, p. 44). Lines 25 ff., "In te nunquam nubilata," may be compared with a passage in St. Cyprian's De laude martyrii:—
"All things there have nothing to do with either cold or heat; nor do the fields rest, as in autumn; nor again does the fertile earth bring forth fruit in the early spring; all things belong to one season, they bear the fruits of one summer: indeed, neither does the moon serve to mark the months, nor does the sun run through the spaces of the hours; nor does the day, put to flight, give way to night; joyful rest reigns over the people, a placid dwelling contains them."
Dr. Neale's rendering of the lines 25-30 is:—
"There the everlasting spring-tide
Sheds its dewy, green repose;
There the Summer, in its glory,
Cloudless and eternal glows;
For that country never knoweth
Autumn's storms nor winter's snows." [Rev. W. A. Shoults, B.D.]
Translation in common use:—
Light's abode, Celestial Salem. By J. M. Neale, published in the Hymnal Noted, 1858, in 7 stanzas of 6 lines, and again in his Hymns chiefly Mediaeval on the Joys and Glories of Paradise, 1865. In its full or in an abridged form it has been included in several hymn-books, including Hymns Ancient & Modern, the Hymnary, &c. In the Hymnal for the use of St. John, &c., Aberdeen, Appendix, 1870, it is altered to "Seat of Light! Celestial Salem," and in the St. Margaret's Hymnal (East Grinstead), 1875, as “0 how blessed, 0 how quickening."
--John Julian, Dictionary of Hymnology (1907)