Just tested as I was unsure about potential limitations in horizontal middle potentially being hard-locked in resizing for an empty, left column. Even in Fibery’s current MD functionality the indentation functionality should be acceptably be able to work around using 2- or even multi-column.
Which makes it actually better, faster and more reliable than regular indentations, providing tabular style of flexibility and structure. (The left-most column would obviously remain empty for specific indendation-preference). Combined with above paragraph’s potential implementation idea it might be a very fast, reliable and compatible/practical solution. Indendations are imho overrated, especially with classic, non-professional implementations.
From my current experience copypasting between separate fibery-MD documents would always keep desired MD-formatting and data. Auto-Indexing order within columns also seemed to work as aspected; Left to Right, top to Bottom.