Complex sentence: Isildur is not recorded as having given up his rights over Gondor, and Meneldil is described at being well-pleased by his departure; but equally, there is no record of Meneldil publicly claiming at the time that Isildur had relinquished the throne.
Split into simpler sentences: Isildur is not recorded as having given up his rights over Gondor, and Meneldil is described as being well-pleased by his departure. Equally, however, there is no record of Meneldil publicly claiming at the time that Isildur had relinquished the throne.