Agent Scripting API 400 on Complex JSON Payload

Is it possible to define nested conditional logic within the blocks array of a new script via the Architect API? The documentation suggests simple linear structures, but our integration requires dynamic branching. Sending the payload below triggers a 400 Bad Request with an invalid schema error. The SDK version is 2.1.0.

{
 "name": "Dynamic Script",
 "blocks": [
 {
 "type": "condition",
 "condition": "{{customer.tier}} == 'Gold'",
 "thenBlock": { "type": "text", "content": "Welcome VIP" }
 }
 ]
}