Unfortunately, the custom component data doesn't get mapped to the form's state, formName.data. Is that what you are looking to do? You might be able to solve for this with some Javascript that combines the custom component state with the form (instead of directly using formName.data)
The custom component interacts with other app plugin values through the inputs. For example, you can make your "label" input dynamic based another Retool component's value (see screenshot).
Let me know if it sounds like I'm misunderstanding any of your questions. If you have a specific example of a set value issue that you're working on, please feel free to share!
Still curious to hear @abusedmedia's thoughts, but this is my two cents