I’m not 100% sure if I understand you correctly but here are some tips.
The propagate tool can be used only on highlighted keys and channels (it doesn’t have to paste over every channel). This makes it perfect if you need to change the x loc of a foot w/o changing anything else, for example
There is no way to offset later values by a certain amount, but you can select keys in the graph editor and translate them in the viewport. Combine this with the hotkeys to constrain it to the y axis and to a certain value to achieve the effect you are after. (eg – select the x loc keys > g > y > .85 > enter; this will move the selected values up .85 on the y axis of the graph editor)
Or you can do the same thing without knowing the exact value by constraining with the middle mouse and dragging them all up (or down)
But I have a feeling that you will just get used to doing it the fastest way you can find. Most of the time that it just with the auto-key and dragging it around and flipping in the viewport.
You can use the root control to fix stuff like that but I would highly advise against it at this stage. It becomes difficult and messy to keep track of where you made an ‘animation hack’ so it should be the last resort.
Hope that helps.
