Update:

convert -coalesce -fuzz 10% -transparent "#fb665a" "/home/user/0 1.gif" "/home/user/0 2.gif"
convert -background white -extent 0x0 "/home/user/0 2.gif" "/home/user/0 3.gif"

I've now discovered a way to color the background, but the final IMAGE_2 is still flawed.

There is a problem in IMAGE_1 with the color that should previously be replaced by transparency.

I don't know how the area to be replaced can be expanded so that the similar adjacent color is also captured.