Would it be possible to add pre-requisite health check in the gui? (similar to Distributed Switch health check) It would avoid trying to fix a deployment not working.
There could be multiple level of health check:
Confirm that all objects have been properly created in the API.
(Maybe the logged in user would not have the right to see such settings so this test should run under a different account)
Confirm the logged in user has all prerequisites permissions.
Then the user select in which organization network to simulate a deployment:
Confirm network has an ip pool configured with enough free IP address
Confirm DNS are configured.
Confirm the EDGE is properly configured with access to a load balancer,
Confirm Enough external IP addresse available
Confirm enough VIP available in the edge.
Confirm enough capacity (CPU/Memory/Storage)
Confirm sizing policies created.
Then deploy a test VM in this network (similar to how the ephemeral VM would be created)
Confirm that the test VM has access to DNS server
That the VM has access to all URLS needed. (List should be provided in documentation, not all environment can provide full internet access)
That the VM has access to Cloud Director (and eventually if certificates are trusted)
If all test results passed/failed are visible in the gui, it would be easy to pinpoint wrong settings and fix them before even trying to deploy a cluster.