I think you will need to manually update the position of the character. Let's say you know that at 100% the character will move 20 pixels, so you will need to calculate the actual pixel amount based on the current scale of the character.
Add this inside of the last frame of the animation - edit as needed...
local pos = game.CurrentCharacter.Position -- store current character position
local perc = math.floor(game.CurrentCharacter.Size) -- store current character size (rounded up)
local amt = 20 -- amount of pixels to offset at 100% character size
local offset = (perc / 100) * amt -- calculate the offset
game.CurrentCharacter.Position = {x = pos - offset, y = pos.y} -- update the character position
Quick note: it's untested, & the example is for jumping left. edit the x, y bits of the last line as needed.
Newbie
Imperator