This is probably the wrong forum to seek support for Firefox. I was merely pointing at the possibility of using Open Web Apps for this instead of Fluid.
Would be cool, if you could add an issue with more information about remoteStorage.js not working with your desktop FF OWA installation. Last time I used that, it worked just fine.
By the way, this blog post might be of interest to anybody, who’s not familiar with cross-platform Open Web Apps: https://hacks.mozilla.org/2013/10/progress-report-on-cross-platform-open-web-apps/