There is a feature request to expand the option for Collection Project filters which includes observation fields: https://forum.inaturalist.org/t/add-tags-observation-fields-threatened-status-description-choice-s-to-populate-collection-projects/8639
As for the main topic of this post, I agree with the the responses about mimics not fitting into the taxonomy system. Other than that I agree it would be nice if species complexes could automatically get RG, but that’s been vetoed by staff: https://forum.inaturalist.org/t/make-observations-with-a-species-complex-level-community-id-automatically-become-research-grade/15226