This is an excellent adventure.

It hits all the right notes of combat, social interaction, and exploration. The story is believable and solid, while the setting is underused in current AL-legal material resulting in a unique play experience.

Some of the combat is too easy, Gith warriors aren't close to being a challenge for most tier 3 parties, at least not at the numbers involved. Other combat offer a good amount of challenge though, the inclusion of creatures showcased in Mordenkainen's Tome of Foes is welcome. It should be noted that those creature in particular are included in the module, meanwhile ones found in the Monster Manual are not so don't forget your books!

The only other criticism I can offer is that it isn't clear how the characters are transported to the Astral plane, it would be helpful to know if they are plane-shifted or astrally projected there.

Nice work!