A Question about Worldbuilding/Terraforming

in the Anime 'Kaina of the Great Snow Sea'

I have a question for the people about the worldbuilding behind the anime 'Kaina of the Great Snow Sea', which is based on concepts by Tsutomu Nihei, who also did BLAME, Biomega and Knights of Sidonia'.

(Spoilers for 'Kaina of the Great Snow Sea')

Its not clear if this is set on earth in the distant future or another world.

The planet is set gigantic 'Spire Trees'. These have a treelike surface but are titanic. They reach vertically up to the stratosphere and spread out into an interwoven translucent covering around the entire planet.

Humans can walk on this canopy, (using breathing gear), and it has its own ecosystem.

The Spire Trees are set at regular intervals.

Below, other than the trees, the entire planet is covered with the 'Great Snow Sea'.

This sea is absolutely not made of water. It seems to be some kind of heavy gas, held in place by the tree-pollen surface.

The Spire Trees continually drop what people call 'pollen'. These are white hand-sized spheres, heavier than air, a bit heavier than balloons. They seem to be highly 'neutral', they don't really interact with anything, nothing seems to eat them and they are never seen to decay. Nothing seems to break them an no-one tries so perhaps it might be near-impossible.

These white spheroids cover the 'snow sea' entirely; its surface is made up of them.

If a human goes into the Snow Sea, they fall pretty fast. (They can't 'swim' in the Snow Sea' unless they have special gear that gives them buoyancy). They don't seem to get wet at all. They can't breath in it but someone with breathing gear can walk about on the bottom. The Sea is also pretty clear, light doesn't seem to degrade much down there.

There are life forms that can live and 'swim' in the Snow sea. These may be deliberately engineered. They don't swim in the manner of fish but some quality of their sharp long static fins seems to propel them through its substance. If you can get one of these fins off the creatures after death it seems to retain its properties.

Down on the 'ground' below they surface, there seems to be water and the Spire Trees draw water up from there. Tapping the trees for water is how most people survive on this world.

(Yes those do look a bit like ancient rockets being used as towers)

It becomes clear over the series that this is a deliberately engineered environment at every level. It seems to have been a very, very long time since anyone on the world fully understood this. The ability to read is rare and the only reading materials left are metallic, maybe plasticised signs.

The world also seems to be dying at the point of the story. The water of the Spire Trees is running out and the cultures at their bases are preying and warring upon each other. No-one remembers the deeper context of this world.

(BIG SPOILERS AHEAD)

The end of the story is that the heroes find the huge 'Main Orbital Spire Tree' which is still active, they defeat the science cult that rules there and who want to save the world by cutting down the trees. To do this they need the 'Suit of the First User' and their Visor. They use these visors to control elements of remaining hypertech and they need the clearance the Suit and Visor will give them. To find these they are sending slaves down to mine the 'First Site' at the base of the main tree, under the Snow Seas surface.

The good guys get this suit eventually and, since the hero knows how to read and the operating system that still remains (in the Trees somehow?) likes him, they get to utter the command; "Complete Terraforming".

This causes the spire trees to seperate at their middles and their upper parts to become a series of orbital rings around the planet.

It also causes some kind of reaction that dissolves or changes the White Sphere/Strange Gas nature of the Snow Sea, and turns it all into fresh water.

So now these people live on an oceanic planet on a range of regularly spaced islands made from the bases of the old Spire Trees.

What it seems to be is an alien world with a just-survivable environment, with a human colony that has used massive global biotech and hypertech to fundamentally change the arrangement of chemistry on the planet, making the Spire Trees to guard or contain the environment and the ‘pollen’ to seal in the gas-sea, and to give it a ‘surface. Then at some point the ‘pollen’ and gas are altered or combined to produce water, leaving the bases of the Spire Trees as liveable islands. A plan that took so much effort, and took so long, that the humans who lived there fell into conflict and forgot why they were there, or how the plan is meant to work, (most can’t even read).

So, my question; for anyone familiar with physics, chemistry, worldbuilding, terraforming or similar is; is this an even slightly scientifically worked out concept?

I realise most of it would be hyper-biotech if it actually existed, but the whole setting seems so deeply and carefully worked out that I would be really disappointed if there was simply no way it could be happen, or if its was just magical 'science' writing.