First rainbow goblin after transmogging my DH to look like Goblin Slayer yielded results. Highly suggest doing so as a legitimate farming strat : r/Diablo
Diablo 3 - HOW TO FIND RAINBOW GOBLINS - COSMIC WINGS FARMING (WHIMSYDALE) - PWilhelm - YouTube
Farming For Pets and Wings
It's Just Wings Shows Power of Online-Only Restaurant Brands - Bloomberg
Dreamwalker's Guide for Farming Cosmic Wings - Diablo III General Discussion - [read-only] Diablo Forums - Forums - DiabloFans
Cosmic Wings delivery-only restaurant now available on DoorDash and soon on Grubhub - pennlive.com