If using the formentry module 5.x and below with the Sync Module you must take care with how the concepts are developed. Formentry still depends on internal concept.concept_id values being the same on all servers. The sync module cannot guarantee that to be the case. So all concept/form development must happen on one and only one server in your sync network. This is also the case with Metadata Sharing Module. Work is underway to fix these problems.