One feature that Renoise lacks that a lot of other trackers have is the ability to toggle between sharps and flats.
I think this should be added, along with a third option for a microtonal mode. The option to switch between these 3 modes would be in the transport toolbar next to the octave switcher, and the choice would be saved per song.
In microtonal mode, you can choose how many notes per octave, and the notes will be displayed as numbers. For example, in 31edo, note 29 of octave 3 would be shown as 29-3.
To make this feature useful, there should be native support for loading .scl files (per instrument, like in OpenMPT).