More detail the merrier!
It looks like there’s going to be some soundsets that will be consistently used between multiple chapters, but that’s only to be expected when you have consistent foes.
Nighttime village combat - I’d recommend combining Farmland’s “Nighttime” with Brindle Town for setting the ambiance, then swapping out Brindle Town for Goblin Battle+Kobold Lair during the fight. Maybe chuck in some sounds from Tavern Brawl or from Bandit’s Cave’s In the Cave “Goroc’s Gang” for deeper, Medium-sized humanoid voices. You can use Tavern Brawl (minus the music and plus some weapons’ sounds from Bugbear Battle) for if/when a fight is indoors. For the blue dragon breath weapon, there is one specific to that in Xin-Shalast. Or you could use the lightning spell one-shot, though that is a smaller sound. I presume this half-dragon is a half-blue? The lightning spell one-shot could be his breath weapon. If not a half-blue, other breath weapon sounds could be pulled from Ezran-Male Wizard (acid spray, ray of frost) or the flamethrower universal one-shot.
You could use Farmland for grassland, as that has the sounds of grasses/crops and insects/birds droning day or night (you might want to toss in the “cicadas” element from Tiller’s Marsh, because nothing says hot summer’s day to me like cicadas). Fights with the stragglers could be done with the fight sounds of the previous chapter (Kobolds/Goblins/Goroc’s Gang/Bugbears, etc), minus the Bridle Town sounds. For the camp, use Farmland (of the appropriate time of day) combined with Friendly Tavern or Seedy Tavern. Turn off the chair noises that indicate indoors, and pump up the sounds of the fire so it sounds like a proper campfire. It already has sounds of coins and whatnot, so that’ll do for trading.
For the cave, you can use Dragon Battle (use the Baby Dragon sounds for the drakes, or the hisses from Flying Fiend Battle), with Dungeon Depths or Flooded Cavern for more echos/ambiance. Kobold Lair has your kobold sounds and trap sounds (the baby dragon sounds from Dragon Battle or Flying Fiend wing sounds will suit to put wings on your kobolds) and your bats can be the one-shot “swallowtail release” from Attack on Sandpoint if it’s just a swarm, or use Skaveling Battle if it’s more of a combat scenario. You can use “acid spray” from Ezran-Male Wizard for your acid trap specifically, and your collapsing ceiling can be the collapsing bridge one-shot from Mountain Pass (if the ceiling is wood) or the crumbling building one-shot from Red Dragon City Raid (if the ceiling is stone).
For the fights: Bugbear Battle for the half-dragon and beserkers (along with appropriate breath weapon sound, if necessary), In the Cave “Goroc’s Gang” sounds for the women (with female fighting sounds from Kyra-Female Cleric and Merisiel-Female rogue), Bugbear Battle or Kobold Lair with maybe some hisses from Flying Fiend Battle for the Troglodytes, and for the roper… Does a roper even make a sound? Not sure, but I think you can use the “Thrushmoor” set, specifically the “Killer Vine Battle,” because that sounds scary and rope-y enough.
You can use Wagon Journey, minus the actual wagons (unless your party has them, because I know my players always want lots of space to store their stuff, and someone always wants to travel in comfort and style) for the travel, with Magnimar for the large city and River Journey for the docks. Friendly Tavern will do for your tavern, with bringing in some of the weapon impact universal one-shots or the “axes and shield” element from Bugbear Battle (for sparring/weapons training), and the horses sound from Wagon Journey (for horseback riding).
For the traveling via sailing - use the River Journey set, and also a High Seas set, depending on the size of your river (or if you end up sailing to Waterdeep via the ocean). Baldur’s Gate/Waterdeep can again be represented by Magnimar soundset, and River Journey has a “dock” mood, for when you’re embarking/disembarking. For your fights, Bugbear Battle will suit for hobgoblins, In the Cave’s Goroc’s Gang for guard fights, and Tiller’s Marsh “Spider!” mood for spiders and ettercaps.
Waterdeep will be Magnimar again, possibly with a little of Brindle Town’s “busy market day” for the dock market. Going north, there is a “Swamp” set, and also a “Jungle” set that you will likely be using heavily for most of your moods. Tiller’s Marsh will come in handy too. Bugbear Battle and In the Cave’s Goroc’s Gang for a lot of your humanoid battles, with elements from Swamp and Kobold Lair (and possibly the lizard hisses from Mountain Pass, or the angry hisses from Flying Fiend Battle) to cover the rest of it. You may want the Ogre Battle if you fight a troll. If you want a nasty insect swarm, and have the Sci-Fi player, use Swarm Attack sounds.
At the roadhouse, Friendly Tavern. For exploring the swamp, Swamp and Jungle and Tiller’s Marsh again, with a lot of the same enemy sounds above. There actually is an “Alligator Battle” mood in the soundset “In the Waspnest” if you encounter a crocodile.
You could use a little of the magical resonance sounds from Shimmering Veils for the will-o’-wisps, to give it a creepier element. Dragon Battle’s “sleeping dragon” mood, combined with Swamp sounds, would do for the Black Dragon encounter, if the party is not foolish. If they are foolish, use the Swamp sounds combined with the Green Dragon sounds as the dragon casually annihilates the party.
Castle in the Swamp (…“everyone thought I was daft to build a castle in a swamp, but I built it anyways, just to show 'em!”). Your enemy sounds, same as above, you know the drill for these folks! Inside - Dungeon Depths with some dripping sounds/elements from Flooded Cavern. There’s a major teleportation sound in the Hell soundset for when they get whisked away.
Not sure where this hunting lodge is. If somewhere cold, use Whispers on the Wind’s “inside Vekker cabin” mood. If warm, use Stockade’s “Thistletop” (coastal, warm). Or you could modify either, depending on the clime. Helmed Horror could be done with Bugbear Battle but with the growls/curses turned off and some magical resonance from Shimmering Veils turned on. Gargoyles could be done with Dream Quest II’s “Ceramic Guardians” combined with some wingbeats from Grioth Battle and claw scratches from Dragon Battle. Female Human spellcaster could be done with the Board Game Players Spellcaster - Sorceress. Grioth Battle wing sounds would work for the Perytons.
Brindle Town for Parnast, with Friendly Tavern turning into Tavern Brawl if necessary. Grioth Battle for transportation. For the giants, you can use the Stone Giant battle. The “At the Door of the Cavern” mood for the courtyard, with “Deep in the Lair” for the Indoor Halls, with Dungeon Depths for the caves. Kick up the wind with Elements: Wind to remind them they’re in a floating castle. Maybe chuck in a little of the magical resonance from Shimmering Veils, at a low level, to represent the magic holding the castle up. You can use the stone giant sounds from the Stone Giant battle for the cloud giants, and use the “mists” element from Elements - Horror for their obscuring mist and fog cloud spell-like abilities.
For ogres, use Ogre Battle, human fighters we’ve already covered in the previous chapters, stone golems you can use Mask of Death chapter 3, Golem Battle. Wyverns you can use Grioth Battle. Wizard you can use Board Game Players’ Spellcaster - Sorcerer (or Ezran - Male Wizard). For a vampire you can use Castle Ravenloft’s “vampire attack.”
For the white dragon, use the White Dragon soundset, maybe with some echo elements from Dungeon Depths or Flooded Cavern to get the ice cavern effect.
If the castle crashes to the ground, you can use the crumbling building one-shot from Red Dragon City Raid, and the hurled stone one-shot from Stones Over Sandpoint. And chuck in the shattering explosion universal one-shot for good measure. Maybe some lighting crashes from Storm. And some screams from Goblin Battle. Throw in a universal one-shot Wilhem Scream to put the cherry on top.
I hope that helps!