If there are two shifts on a screen with a timed shift and you move to a second untimed shift after being on a timed shift, it seems to combine the shifts together occasionally, but in such a way that seems based on the timing of when you leave the timed shift and enter the untimed shift's area. Also, both of the shifts are being used as a shift on touch.
To explain further, I had two separate screens that are the same except one has a laser and one does not. This is before the feature of shift saving, so to create "fail states" I was using a shift that goes to a further duplicate that would have an animated death screen based on using the relative placement of a trigger. So you would shift from being "hit" with the laser into a death scene. The laser itself is just a separate shift. But initially to have the laser be an obstacle rather than a wall, it turns on and off in intervals using timed shifts which push Juni back and forth through two screens. Except the area with the laser shifts Juni into the death screen instead. The problem is that it seems to combine the shift-on-touch timed shift with the separate shift-on-touch untimed shift. So if I want the the untimed shift to go ShiftXMap(A)=2 it will actually shift 3. And the only thing I can think that's making it happen is the that the timed shift is saying ShiftXMap(B)=1. If I test level directly onto the Shift A it will work, shift to the death screen and sometimes the timed shift will not result in this error, the unpredictability of it makes me think it can only be the timed shift. On other screens using ShiftXMap(A)=1 and ShiftXMap(A)=-1 ShiftXMap(B)=1, The negative 1 sometimes wins over the B in this case and doesn't add them together but it just becomes -1.
I've also experienced screens that appear to be correct but the geometry is wrong, like it's showing me one screen but the collision masks and the shifts are of another. I've also seen the opposite where I've shifted into void screens only to have a shift suddenly work and then I'm out of the void screen and into the screen I was supposed to have shifted into in the first place. And this has also happened when exiting a screen that uses a timed shift on touch back and forth between two screens and when leaving either screen using a warp, though this is much less likely to cause an error, I do believe it can and I believe that it's, again, caused by using a timed shift-on-touch in a near screen encompassing manner or simply having the timing be very close to another shift's activation when it's shift-on-touch.
I've also found that it finds certain shifts more acceptable than others, in the way that it is removes likelihood of the error if instead of having the final "death" shift screen X=3 if you put it below as Y=1, it doesn't seem to add them together. But even with using a shift of Y or X instead of Y with whichever one of the timed shift-on-touches are originally using there are some strange results with the second shift that results in the death screen. Sometimes aspects of that shift-on-touch will not activate, if it says "stop music" only sometimes will it stop music even if it shifts to the correct screen. As if maybe the other shifts are retaining the aspect of the timed shift-on-touch while still using the other shift-on-touch to tell Juni where to go.
In general I'm just finding timed-shifts used anywhere near other shifts and even warps have really unpredictable results. Granted, they're probably not supposed to be used this way and the save-replacement shifting can produce the same results but I created a lot of content for these timed shifts already. If you need me to upload what I have my level to show you what's happening, I will. Though it's really hard to get predictable reproduction of bugs when it comes to this problem.
Screw it, here's the level:
https://www.dropbox.com/s/3jzfb7wwe5eb1gt/plural%20-%20The%20Empty%20Planet.knytt.bin?dl=0On x1053 y1037 is the easiest way to see the error because it reproduces most easily. Shift B on that screen is supposed to shift X=2 but it will Shift X=3 into a void screen many times upon exiting the timed shift's area of Shift A, into the Shift B area. If you "test level" starting inside the Shift B it will work correctly, but if you test the level outside in Shift A then go into Shift B, it will, more often than not, in my experience, go into a void screen.