1. In the DBA view, connecting to the CDB root of a RAC database and expanding the 'Container Database' menu, each PDB is shown for every instance (select from gv$pdbs). Clicking on PDB to see the details, there is no indication which instance it corresponds to.
2. Creating a new PDB in a RAC multi-tenant database give ORA-1427 for every character typed in the new PDB name (again, selecting from gv$pdbs returns a row for each instance - probably want a 'distinct' somewhere...)
Thank you very much for pointing this issue out. I've raised a bug, and it will be fixed in a future release.
SQLDev Development Team