It looks like this product only works with the 12 characters it's designed for and needs SubD level 4. My guess is if it's not one of those characters it won't conform correctly to the figure's face. I don't think the eyelashes themselves are involved with conforming.
What problems are you getting?
The shaping options only appear on the default G8F lashes. They won't appear for anything else and there is no option to attach it to anything else. I am not sure how its attachment works. If I add an alternative eyelash and hid the default G8F eyelash the tears are hidden as well.