Isn’t light also the aspect that has a lot to do with knowledge and stuff? If so do you think Vriska could use her power to steal knowledge of what went down in the gameover timeline if she used her powers for that purpose?

Her power itself is more related to Luck, but it could be for other Thieves of Light. Even then, she does generally just, gather intel on the post-retcon Timeline and the LE-killing Weapon.