No.
That bower fetched version of plonetheme.barceloneta is only used for building the CSS with class names supported by Mosaic Editor. Otherwise the visible Barceloneta theme comes from buildout installed plonetheme.barceloneta release.
Please, go through the Plone 5 theming training material on how to copy an editable version of the current theme https://training.plone.org/5/theming/ttw-advanced.html#copy-barceloneta-theme
Alternatively Mosaic repository contains a configuration for my Webpack based theming approach Plone 5 frontend development plugin for webpack, but I have not tried if it still runs directly from the checkout https://github.com/plone/plone.app.mosaic/blob/master/README.rst#webpack-based-frontent-development