This is more a feature of Luban and not the machine. Any mainline free slicer has this feature, called “one at a time” in Cura (which Luban is based) and “Sequential” in Prusaslicer. Prusaslicer comes pre-loaded with snapmaker profiles for all the machines single/dual/quickswap/etc., install and go.
This one is a bit technical. The problem being is you may see a mistake, and it might only be a mm down or something, but the actual line of the gcode may be hundreds of lines back depending on the settings, model, etc. It would be almost impossible to reverse back to that line specifically in the controller. However, CNC kitchen did a video on this if you wanted to measure and manually edit the gcode.
Again, this one is more about the slicer, Luban, not the machine. It supports it, however.
If it’s at a certain layer, the M600 colour option. It’s built into almost every slicer as I outlined above about sequential, or you can do the manual insertion method.
If you just want to change mid-print on a project already running; either tap the pause button and open the tension door and pull the filament out, replace with new. Or, simply snip the filament at the top of the extruder, and let the filament runout sensor kick in to change filament.