This is really great and I would not know where to start building this. The only thing that I would like to have is the use of "modern" JS tech like ES6 and a build pipeline... Surely this can be added later as well.
In a project I worked on I used SVGs from the designer and animated them with Javascript (Velocity.js in this case). The trick here is to inline the SVG into the HTML page (can be done with a preprocessor). Then the SVG DOM nodes can be animated as you like.