For the outline pumpkin it’s OK to use high contrast yarn. I think the Fall Banner will look better with solid-fill patterns than outlines, but this Pumpkin Outline might be useful for other purposes.
The Pumpkin Outline is a more natural pumpkin shape, not uniform from side to side.
Pumpkin Outline — Right Stem
Sample — L1-3: RHS “Tangerine,” L4: YBSS “Olive”

You may want to alter the instructions for the stem a little bit. Look at the diagram and decide which stitches you want to use.
Pumpkin Outline — Left Stem
Sample — L1-3: CSS “Pumpkin,” L4: RHS “Guacamole”