The relevant documentation suggests that the fields displayed in Relevance Search results depend on the field order of the Quick Find. However, the way Relevance search works is that the fields with “hit highlights” override the fields with no hit highlights, so users are unable to see each of the entities they set in their Quick Find customization. Relevance search should be able to be customized using the Quick Find columns as the documentation suggests it can be, but it actually cannot in practice.

Relevance Search Documentation:
https://docs.microsoft.com/en-us/power-platform/admin/configure-relevance-search-organization