Great question! It would be nice to hear back from Twitch staff. Last August I posted a question about a feature from v5 that is missing in Helix, and never got a reply. I even included links to two other posts about the same missing feature, neither of which were actually resolved.
It’s frustrating when you take the time to study the documentation, learn the ins and outs of both the old and new APIs, are then urged to migrate to the new API, ask detailed questions seeking guidance about missing functionality, only to be ignored. FeelsBadMan