Ok as I just did the process again to give access to the Turkish team it appears we cannot create any more organizations with our main account, or at least we cannot create new organizations under the same unlimited access.
So, the organization needs to be as follow:
The OFN organization is hosting all the guides. But admin/writers/readers permissions can be given towards members or teams per guides. So a maintainer of a particular language does not loose control over the content and can always decide to migrate somewhere else if they hate gitbook. I have created one team per language. The OFN global user (in bitwarden) has access to everything (so for English user we should really not use this account to edit content, to avoid mistakes 
) so I arranged all guides by language thanks to the group function:
As the dutch and german guides were not written yet, I took the liberty to migrate them to the OFN main account and give access to the proper teams ping @Theodore