Yeah using C3 in NWJS has been an unpredictable mess whenever I've tried to use it - And believe me, I've tried to get it stable and working. But I constantly dealt with losing save data (silent crashes often happened, even on fresh new Win10 install), having to delete my Appdata and reinstall plugins over and over again, etc.
I have had the smoothest experience by using C3 in Chrome. My project is 100% NWJS based, so I test using Remote Preview and the Remote Preview Tool (Found here).
Not a single silent crash or anything when using Chrome.