" or "Ein diskreter diplomatischer Schritt". "Quiet" means low-key, so "unauffällig" or "leise". I'll use "Ein unauffälliger diplomatischer Schritt" but "quiet" can be "leise" in the sense of not loud, but here it means not publicized. So "Ein diskreter diplomatischer Schritt" is better.
Then: "The Omani leader's arrival in Doha wasn't announced with fanfare. It's the kind of low-key visit that often matters most in Gulf diplomacy. Oman has long played a go-between in regional disputes, and this trip fits that pattern."
Translation: "Die Ankunft des omanischen Führers in Doha wurde nicht mit großem Tamtam angekündigt. Es ist die Art von unauffälligem Besuch, die in der Golfdiplomatie oft am wichtigsten ist. Oman hat seit langem eine Vermittlerrolle in regionalen Streitigkeiten gespielt, und diese Reise passt in dieses Muster."
"go-between" -> "Vermittler" or "Mittler". I'll use "Vermittlerrolle".
Then: "The timing matters. Washington and Tehran have been stuck for months, with no clear path back to negotiations. A fresh channel through Oman could give both sides room to test ideas without public commitment. The visit is seen as a way to nudge
