I’m facing similar challenges as I’m sure many designers do. Especially validating concepts in html vs a mockup. Tests just aren’t real until the product feels real. At a previous job we ended up with a front end dev as part of the design team and built a bootstrap based framework that let us put together pages quickly using such a design system. That works well for larger orgs that will use the design system for a while. That said a kick ass developer can code your prototypes as fast as you can fake them in Axure.