Importing Full Width Image Shapes from Illustrator into Rise

I don't see anything but a nice crisp line. That artifact you show in the screenshot is not consistent with how a vector image should display. Vectors are drawn by the browser and don't have pixels so it will be a straight line.

I did find this info below on a site explaining SVG. Perhaps the resolution of your monitor is what is causing the aliasing. I did load the demo course on a smaller resolution screen and scaled it down and did see a little artifacting. So it appears that lower resolution monitors will experience some artifacts, but there's really nothing you can do about that. 

"Your computer screen is made of fixed-size pixels. A diagonal line can look jagged as the computer translates it to the nearest pixel blocks; this is known as aliasing. Alternatively, the computer can use anti-aliasing to soften the edges, blurring the line across all pixels it partially overlaps.

Most SVG viewers use anti-aliasing by default, and this can sometimes make a 1-pixel black line look like a 2-pixel gray line, because it is centered on the space between two pixels."