Well, what feature would help with this and how would it work? Things like uneven scroll updates are due to maths, not the technology.
That's just it though, I've been thinking on and off for a year or so on this topic and really haven't found a good solution. Many objects have to be synchronized (camera, player, etc...) so that makes it a hard part to make part of the engine right? I mean how is construct supposed to know what you have moving and whats not and which moving objects matter. The only thing I could figure is that some sort of behavior could be applied that looks at the objects last position that it rendered to, and its new render position. If the difference between oldx and newx is greater than oldy/newy, then it only updates y render position when x render position updates and vica versa. This can eliminate stair stepping mostly... I have a project from a year ago that does this... I just stopped doing it though because via events it starts to take a toll setting and resetting object positions twice a frame, storing the old render position and the "real" position... and so on- especially when you have many dynamic objects. As it stands I don't think there is a way to even tell the c2 renderer to render this sprite at an offset (you could do that via an effect I suppose... but again performance can tank if you have many actors) which would be helpful (actually it would be cool to be able to change the objects render setting in game - you know, draw it this big, at this offset, at this color, using this blend mode (x,y,sx,sy,rgb,mode).
On a side, I was running a nes emulator on my laptop when I was talking about nes games... They have something going on like what I described above to ensure you get that nice pixel line instead of thicker stairstepping lines (like the middle image I provided)
---- My current practical solutions via c2
In general, these days I turn pixel rounding off and then make sure I have my camera position make sure it is only updated if the actor it is following would have had a visual rounding. the stair stepping is usually only obvious when using lower resolutions. Or the character is moving at a steady angle.
This is a stupid way to do it but I also sometimes make pixel art, scale it up in Photoshop using nearest neighbor (to like 4x or 6x), then I run the game with linear and no pixel rounding at a decent resolution. Its not as crips as pure pixels but You get amazingly smooth everything including scaling the screen, and zooming in and out. It takes longer to make all the assets, and it does less well performance wise, and if you use tilemaps you have to fix that... but you get the gist.
Of course, it bears noting as you said, this isn't a c2 specific problem but, as you noted, a problem with trying to emulate crappy hardware of the 80s on a modern platform. Unity has the exact same problem... only it can get worse because you have to deal with fixedUpdate and regular Update syncopation and how the game interpolates position if you are rendering faster than updating fixedUpdate,
Sorry for the Long read, I'm trying to be brief.... lol