Hi Daniel,
You can follow the following steps to programmatically retrieve the Component under Test.
1) Use sltest.harness.find to find the test harnesses associated with a particular model or block.
% Assuming 'modelPath' is the path to your model or the block you are interested in
harnesses = sltest.harness.find(modelPath);
harnesses is an array of structures. Each element in this array represents a test harness associated with the specified model or block, and the structure contains information about each harness.
You can use this array of structures to access the information about Component under Test. Please note that the struct itself does not directly contain a property with the name "Component under Test", but in my case the property "ownerFullPath" contains the same information as displayed under "Component under Test".
harnesses(2).ownerFullPath
I hope this helps.