In lieu of having this native I’ve wondered if a tool could manage it. As a “maybe good enough” approach I was imagining a floating window with a read-only view of the current pattern state. It would update as the pattern was edited. Then you could edit on the centered line but still see the full pattern.
Food for thought.
(edit: This idea was prompted by this:https://forum.renoise.com/t/work-in-progress-piano-roll/48049))