I assume, that if there is sufficient amount of people who sign the petition, it could show Light that there is a relatively sizable demand for the localization. It could become profitable, if enough people purchase the translated visual novels.
I think that it may be possible to raise traction, if the petition gets enough people to sign it and when the games released, there needs to be a lot of demand.
I think raising awareness on r/visualnovels and twitter reddit, about the petition that could lead to the Western release can be helpful.