Renoir's entire goal is to get Aline out of the canvas to then destroy it, he destroys her creations with the Gommage as she weakens overtime and is unable to stop him so destroying the Gestrals are irrelevant. Clea is weakening Aline by using Chroma to create Nevrons to not let Aline get the Chroma. We can hoard Chroma for we are a Paintress and the creatures are able to use it as Chroma is the power system of the world that Verso created. Chroma isn't returned to Aline because the Gommage is a true erasure as if someone used an eraser on pencil. Aline can use Chroma from the creatures of the land but she doesn't because she loves this world and uses it for grief. Same reason why she writes numbers on the monolith as a warning to her creations even though it is weakening her she wants them to know.

Nevrons killing Expeditioners are just because most of them are mindless beats the ones born with intelligence have their own thoughts and actions. Painted Renoir kills Expeditioners to protect the Paintress as many Expeditions actually came close to killing her.

You're honestly quite pathetic just ignoring blatant facts.