Please, go check the second example. There is no looping over cell coordinates.

chunk.area.left_top.x of the -1 chunk -1
equals
chunk.area.right_bottom.x of the chunk -2
without cell looping involved. I find this absolutely incorrect. Please, elaborate how can I look at this the other way ...

In Factorio API
chunk.area is overlapping with another chunk area.

Illustration
Execute following code in Map Editor in
local surface = game.surfaces.nauvis
local newTiles = {}
for chunk in surface.get_chunks() do
if surface.is_chunk_generated(chunk) then
if (chunk.x == -6 and chunk.y == -6 ...

I have defined named noise expression
data:extend{
{
type = "noise-expression",
name = "n1",
intended_property = "n1",
expression = {
https://github.com/ilit/factorio-ambient-seasons/blob/main/data.lua

but cant seem to make it work control stage.
game.surfaces.nauvis.calculate_tile ...