In your specific case, what if instead:
- auto-grid used the “carousel” layout by default or
- it were easier for users to “ungrid” the whole group
Another thought is occurring to me now…
Perhaps it’d be worth further separating the concept of an “image group” from the “layout” for that group.
For example, in the rich editor if you could toggle among three options for a group (list, grid, carousel), while leaving them all in the group, perhaps that’d make it easier for users or moderators to pick the preferred layout with a single click, in the cases where the heuristic chosen to pick the default isn’t what they want.