I’m not endorsing the idea of a species group rank. But one thing to keep in mind that on iNat ranks need to have levels as well. e.g. here are the ranks including and between genus and species:
genus
subgenus
section
subsection
complex
species
So its important for any proposal to include the level of this rank (e.g. where it would insert in this list)
If this is an insect only problem, my preference would be to coerce ‘section’ and ‘subsection’ which is restricted to plants into this use case rather than add entirely new ranks