On server it is possible to have a setup as the following A<>B<>C, in which also changes from A are transferred via B to C and changes from C via B to A.
This can work on server as you can set a different sync user for the different projects. On cloud, however, there is only one automatic sync user (add-on-user). This is the same for all cloud projects and therefore the setup doesn't work automatically.
We should think of an alternative way to make this use case work for cloud.