I thought I'd share a quick script I wrote for myself to move layers with precision (in other words, adjust layers position by the precise number of pixels).
tell application "Pixelmator Pro"
activate
tell its front document
set x_adj to text returned of ¬
(display dialog "Move left/right:" default answer "0" buttons {"Cancel", "OK"} default button "OK")
set x_adj to x_adj as number
set y_adj to text returned of ¬
(display dialog "Move top/bottom:" default answer "0" buttons {"Cancel", "OK"} default button "OK")
set y_adj to y_adj as number
set selected_layers to selected layers
repeat with l in selected_layers
set {x_old, y_old} to position of l
set position of l to {(x_old + x_adj), (y_old + y_adj)}
end repeat
end tell
end tell