Have you tried:
tween = Tween.Linear or tween = Tween.Expo
local larrow = fe.add_image("pic/lArrow.png", flx*-0.200, fly*0.450, flw*0.060, flh*0.120 );
local larrow_move_cfg = {
when =Transition.StartLayout ,
property = "x",
start = flx*0.040,
end = flx*0.080,
time = 1000,
loop=true,
tween = Tween.Expo
}
local larrow2_move_cfg = {
when =Transition.StartLayout ,
property = "x",
start = flx*0.080,
end = flx*0.040,
time = 1000,
delay = 1000,
loop=true,
tween = Tween.Linear
}
animation.add( PropertyAnimation( larrow, larrow_move_cfg ) );
animation.add( PropertyAnimation( larrow, larrow2_move_cfg ) );