I believe the listing process, whether bulleted or enumerated is provided by the Apple TextKit on which the Scrivener editor is based, and so the indentation and tabbing is set within that (black-box) facility. If my memory serves, this has come up previously and KB wrote that to provide his own listing system would be a huge undertaking, as it would not only concern the editor, but he would have to write separate compile-code for each and every compile target. The same is true for tables.
Who outside the inner circle knows exactly what KB is working on at the moment, but in a recent posting§ he said, " I’m full time on other code that I’ll have my hands full with for the foreseeable future", so who knows if that has anything to do with this.
Mark
§ is there a risk that you L&L drop Scapple ? - #11 by paulslater