Apps Endpoints: Only show detailed error message but hide success

tl;dr Is there a way to only display error messages but no success messages in Apps Endpoints? I did not find anything in the Apps Docu but maybe someone already found a way using custom CSS for it?

In my App, I’ve built a wizard like interface where the user enters different parameters and then triggers a function to continue. I would like to show detailed error messages to the user, if a function failed (usually, the user entered implausible values). This error message must not disapear before the user clicked on it. But at the same time, I don’t want the user to spam with success messages (as the user will see in many different parts / data that the function was successful anyway).