In the green section I tried to put lots of lines, a bit like in old drawings where they would make a sort of hatch effect for artistic effect, light, shadow etc.
But the lines are quite boring- is there a package in krita which could be used which gives the lines an interesting variation, almost like you see in the old hand drawn hatched lines with pen/pencil?
Apart from the different brushes that might help, you could also try some methods using Fill Layers and Filters. For example:
Here, I’ve used a Fill Layer to fill my canvas with a hand drawn line pattern I made. I then used a transformation mask to point the line pattern along the trajectory of the space it’s in (for a more pleasing appearance), then used a Transparency Mask to contain the pattern only to the box area I wanted it in.
In the following example, I used a Halftone Filter Masks to apply that same pattern to an image I made (point A) and used a Color Adjustment Filter Mask to tweak the values, as needed. For the second example (point B) I changed the patterns to something more like a crosshatching and tweaked the Color Adjustment Filter to better suit that new pattern.
(Edit: Original example image didn’t upload very well. Hopefully splitting them will work better).