[DiapDealer]

That's not likely to happen. Not because of any kind of rivalry or animosity--far from it actually. But because it's just a bad, bad idea. Too much potential for a We-Break-His-App-He-Breaks-Our-App kind of thing. Not to mention the problems with making two separate projects prerequisites for each other. Kovid's got his own system and he moves fast, he's not going to want to take time to check with us before he makes changes to his code that might be being used by Sigil Reports (and vice versa).

Somebody might be able to write a Sigil plugin that utilizes calibre's python modules if they're available (and that's a BIG "might" considering python modules compiled with different versions of python), but it would never be able to interact with Sigil's built-in Reports feature. And it would always be a fragile thing that could break at any moment (through no fault of the plugin dev).

My toolbox works because all of the tools are mine. There's a dependency on calibre's plugin framework, but that's the same for all calibre plugins: calibre plugin/calibre plugin framework ... Sigil plugin/Sigil plugin framework. And ne'er (or at least very unlikely) the twain shall meet.