The eraser shouldn't be rendered as white, but it needs to rendered(because if it's not that causes the lines that were "erased" to appear) Even reMarkable's official tool has this problem, and I'm really starting to get bugged over it. I don't know how you would code it but perhaps you could modify the code that if any line is covered by eraser, it skips/removes that line. I don't know how you would go about doing it, but this is the greatest problem I have with my rM since the beginning.