I actually don’t know how correct that is, and would love to hear if resting state ICA preprocessing gurus have insights. It’s certainly the case that you need to specify training data or which set of pre-calculated weights to use ICA-FIX, but I honestly don’t have a sense of how sensitive the output is to the choice. If it’s very sensitive to proper hand-tuning I can see that as a reason to not incorporate ICA-FIX into fMRIPrep.
For background, the dataset we’re concerned about here is sort of close to the "HCP_hp2000.RData" description, but not a perfect match. Digging through my notes, we’d spot-checked the identified component images for a few people back in 2016, decided they were ok, and proceeded. Resting state runs are a comparatively small part of the study I’m involved with, and a part I spend very little time thinking about. But that’s not an excuse for neglecting those runs entirely, and if we switch all preprocessing over to fMRIPrep the resting state runs will need to be included!