Searches in 'Discover' are very bad and limited, only find references if the search starts with the word, for example if I search for 'DBGL' does not appear anything however if I search for 'DOSBOX' I get dosbox and two icon themes for DBGL. If I search for 'COMMODORE' for example, the 'vice' emulator does not come out. It's very frustrating, I usually end up finding what I want by searching the internet or looking directly at DPKG. It would be better to look for the entry in the name and description of the elements and sort the results by degree of coincidence.
Hey, I would need to know some more information. For starters though, it sounds to me that DBGL doesn't have appstream information and we are suffering because of it. Same thing for vice, with "vice" with the difference that here the package name matches the application name, hence being found. Still, all applications must offer appstream information to be listed properly. Please report bugs to these projects to offer it. https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html