Specifically, the gods are listed with the following realms on On Hallowed Ground (looking there was much easier than looking at that huge index of the planes – although see the document I posted below.

)
Annam – Outlands/the Hidden Realm
Diancastra – Wanders
Grolantor – Carceri/Cathrys/the Steading
Hiatea – Elysium/Eronia/Woodhaven
Iallanis – Arborea/Olympus/Florallium
Karontor – Carceri/Minethys/the Rack of Injustice
Memnor – Gehenna/Chamada/Thraotor
Stronmaus – Beastlands/Karasuthra/Stormhold
Skoraeus Stonebones – Wanders
Now, of course, this makes it unlikely that I will find anything specific on Diancastra and Skoraeus in the Planescape books, although it’s likely enough that they will be found
somewhere.
Thusly, I found information for the gods and/or their realms in these places:
Annam – PS Campaign Setting, Sigil and Beyond, p 18
Grolantor - Planes of Conflict, Liber Malevolentiae, p 11 and 19
Hiatea - Planes of Conflict, Liber Benevolentiae, p 50
Iallanis – Planes of Chaos, Book of Chaos, p 39
Karontor - Planes of Conflict, Liber Malevolentiae, p 11
Memnor - Planes of Conflict, Liber Malevolentiae, p 28 (very briefly)
Stronmaus - Planes of Conflict, Liber Benevolentiae, p 13 and 27
Grolantor and Stronmaus, unlike the others, have their realms fully described therein. I need to have a look at “The Players’ Primer to the Outlands” to see if Annam is discussed more thoroughly in that minor boxed set.