As far as I understand the issue, a société simple (maatschap) is the only way to build a cohousing. Brutopia and co used a slightly different version (société civile), but that’s only because the law was changed (société civile is the predecessor of the société simple).
According to the Cohousing Projects webinar that I attended (see Cohousing Projects "Masterclass on money and documents", third bullet point) it is mandatory to use a société simple if you build real estate that is not covered by the “Loi Breyne” (which is the case for us).