Lukas,
The wait command raises a Warning message instead of exception so the test is not stopped. The ‘FailureHandling.STOP_ON_FAILURE’ is a little bit confusing. We will consider to make it right behavior.
In order to make the test stop, we could add assert for the command, for example:
assert WebUI.waitForElementVisible(findTestObject(‘CuPaDs/Color/Color’), 3, FailureHandling.STOP_ON_FAILURE)
If the element is not visible within 3 seconds, the wait command return false and will the assert will throw exception to stop the test.