This study exemplifies the importance of high-throughput screening as the initial step for identifying the first example of hitherto unknown molecular classes. Once the first member(s) of the class are known, it can be expanded through traditional exploration of chemical structures. Our work furthermore emphasizes some of the general challenges when screening for new types of molecules with rare properties, such as excited-state Hund's rule violations. When exploring molecular space it is essential to avoid false negatives, and to use methods that are as broadly applicable as possible as we cannot know beforehand what types of molecules will be uncovered.