Just wondering, how are you using ES2015 imports in the browser? Does Feathers come with a built-in module loader parser, or is this a feature of using Vue, or are you doing some other magic?
Feathers doesn't assume much on the client. You can use a module loader or the bundled Feathers client which works right out of the box. To be able to use ES imports in the browser I personally use http://stealjs.com