The Sunreavers were kicked out of Dalaran. They don't live there anymore. They were integrated into the Blood Elf military. The Covenant lives in Dalaran. They are bound by the neutrality of the Kirin Tor officially, no matter how much it may personally rankle them. That they would prefer the Kirin Tor to be pro Alliance is clear for all to see.
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Pandaren are probably one of the most numerous races in the game given they are the dominant population of an entire continent with multiple settlements spread across multiple zones as well as the wandering isle. Canonically, the player Pandaren is the friend of Ji and Aysa from the Wandering Isle, but all other Pandaren (from the perspective of the Pandaren player) are Huojin or Tushui who were encouraged to join the Horde and Alliance respectively.
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In regards to those who are opening portals to old Dalaran in Stormwind, this means nothing. The Silver Covenant is bound by the neutrality of Dalaran, but the members of the Silver Covenant are partisan towards the Alliance, seeking to aid it at every opportunity. That they would handle the Old Dalaran portal is unsurprising.
Of course, this brings up the fuzzy area of the fact that the portal to Old Dalaran is inconsistent with the modern timeframe, as we know Dalaran was moved to the Broken Isles. Were this particular room an honest representation of the game as it should be, there would be no Old Dalaran portal. However, for gameplay reasons, there must be . Therefore, the mages operating the portal being of the group that assisted the Alliance of that time makes sense. I would not rely on this example too much, as the temporal implications can induce headaches.
The Silver Covenant is not neutral out of choice. They are neutral because they are based in Dalaran. They advocate for closer ties between the Alliance and the city, and were clearly at their most successful during the Pandaria campaign. When Jaina ended neutrality after all, they went on a rampage. Neutrality has been restored though and they are constrained again.