Currently IQ data is shown alongside the native fields and is not used for the summary workout data at all in Garmin Connect, thus creating a mess. E.g., ErgIQ app for indoor rowing derives lots of stats from Concept2 rowing machine, but it's not shown in the summary (zero distance, no pace), and splits tables show either empty (distance, pace) or nonsensical info (about 20-50 total total strokes instead of 1000+ reported by IQ, significantly overestimated average and max stroke rate). Also, if IQ data fields are used to substitute the native fields, it would be possible to properly export FIT files to other platforms (such as Strava) with all data fields.
Sorry if this has been requested earlier, couldn't find it.