Make the expectation explicit
Use API tests for contracts and data boundaries. Use E2E journeys to verify the visible behavior across those boundaries with controlled inputs.
Put it into practice
Keep existing API checks and add a focused AuraCheck UI suite. When a journey fails, use both layers of evidence to locate the problem.
Try this on your next release
Choose one journey, define the expected result, and inspect the evidence from a completed run. Expand the suite after the first test is useful.