MS Teams in Cross-Tenant synchronization

This is still a complete cluster F. I have a paid support call opened with Teams, and it went round and round and its now at a stage were its with the developer team they say, yet they said that earlier as well and it wasn't. Because the cross-sync creates the contact on the receiving tennant as something like email address removed for privacy reasons#@companyxyz.microsoftonline.com along with the email address that is correct say email address removed for privacy reasons, it works fine in Outlook and Sharepoint, but cluster F teams finds the #@companyxyz.microsoftonline.com and sends it to that instead of the external email address. This then creates a email request for the other user to accept an invitation to the newcompany's tenant and will give you a second teams account to login. When and if that works (As more often then not it will not work at all and no invites are sent and its just a big hole) users then must switch back and forth in Teams to see messages and get into groups on the other tenant. Its a complete mess for users as they will not and do not get why they must do this, and if they have already connected with them using a email address in teams and its already resolved to "External user" then it gets even more confusing for them. It gets better once Sharepoint sites are also being shared, depending on your address book you might already have two contacts in their and if you share with the wrong name then the end user can't access the Sharepoint site or file and just gets another error. We had to remove the cross-sync (And remove is key as just reducing the scope of synced users will cause other issues as the sync will remove contacts you created in the other tenant as it see's they were not authorized to be synced and will helpfully remove them for you). All in all a cluster F.