Update: Found the issue by using the --debug flag and the sprite api command:
The CLI doesn’t surface the actual error message from the API response
Running sprite api -o dusty-cyanide /sprites -X POST -d ‘{“name”: “test-sprite”}’ -H “Content-Type: application/json” returned the real error: {“errors”:[“sprite name already exists”]}
Turns out my sprites were actually created successfully - sprite list shows them all
The 400/500 errors might be from a post-creation step failing, but the sprite itself gets created