The command set arc.shell.preprocessor.default.command "/usr/bin/cpp" isn't legal arc (the one this forum is about). From googling around, the handbook you're reading (http://altarica.labri.fr/docs/arc-handbook.pdf) seems to be about that link I mentioned above.
Anyway, tell us what you are trying to do, and I'll tell you which of these is better for you :)
I'm a student. Recently, I learning Altarica for analysis a model(system). But I don't kown how to do when I encounter some problems, like I mentioned above. Now, I try a case 'Design of a lift', when I analysis it's safety, it's report a error.