The tool can update a widget's settings in a freeboard dashboard.json file. Takes freeboard dashboard json as stdin, tries to read code.js (react code) and data.js, and then serializes them into the dashboard json.
Install tool as a dev dependency in your react widget project folder (see freeboard-react-widget)...
$ npm install --save-dev freeboard-react-buildtool
Then you can create an npm script to auto-update your dashboard.json with something like...
$ cat dashboard.json | freeboard-react-buildtool > temp && cp temp dashboard.json && rm temp