We won't meet Aletes anymore. As to Argantes, he will become one of the main heroes in the story - and in Gerusalemme Conquistata even more so than in Gerusalemme Liberata. His character too, like Solyman's, will undergo a deep change.
In this episode as it was told in GL, Argantes was given a precious sword by Godfrey as a tribute to a noble ambassador; and immediately after the diplomatic failure, he maintained that he would use that very sword to kill Godfrey in battle. In GC, this excess of impious arrogance has been deleted.
The landscape with the "friendly quiet of the silent moon" conveys a Tassian atmosphere if any. In the handbooks of Italian literature, this kind of descriptions are usually associated with Giacomo Leopardi's poetry at the beginning of the 19th century, but Tasso was the true 'inventor' of it. Btw, the reasons why the atheist and anti-Catholic Leopardi loved the supposedly ultra-Catholic works by Tasso would be worth dealing with. And it will be, at some other time.