It kinda reminds me of MS Access, which ended up being a pain in the butt for IT departments, but also covered a need within some department with limited resources.
Really curious to see where this goes. Do you plan to open-source the client, or simply make the file specification open when stabilized?
I'm currently 50/50 on open source the full app vs just the spec. Since I'm currently having a strong idea of what features and functionality is still missing I feel that open-sourcing right now would distract to much in this phase. But maybe when the main features are done it would make sense to have more people looking at and improving it.