Sorry this isn't in French. I've exactly 0 experience in French and I know Google Translate is terrible so I'll just write in English.
I've been working for a while and I've actually got a lot more information about the calculator than I've published on my blog. I've been able to write a small stub of code which can be placed in the much easier to access "Imaginary Unit" setup menu (accessible through System App -> System Menu -> Imaginary Unit menu, no debug mode necessary) which loads a binary file placed on the flash and runs it. This has meant I've been able to avoid having to flash the device (which can take almost 5 minutes to do) when testing out code. I haven't been able to successfully return from the stub back to the calculator code yet, meaning the calculator must be reset with the rear button once the code has finished running, but it's still WAY quicker than re-flashing every time.
Obviously in having to do this I've investigated the file system functions quite heavily (open, close, fstat, read, write, etc.) and I've written quite a bit of documentation about them. I haven't discovered a system call interface like I've seen on the Prizm model yet, so I'm relying on using the direct addresses of each of the functions to call them from my own code. I'm pretty sure there won't be one though - since the device doesn't support add-ins it wouldn't make sense for CASIO to add a system call interface.
I'm not exactly ready to publicly release my information yet, since I'd like to confirm stuff and build a platform where people can run their own code easily before I do. When I've got that, I'll definitely release something akin to a basic SDK. Then the real work can get started and the device properly investigated.
Glad to know you guys have found my posts and think it's cool.