What is Tamiya panel liner made of ? If it isn’t acrylic,then X-20 won’t remove it,however X-20 will surely remove your acrylic clear and your Vallejo Model air.
If Panel liner is enamel or lacquer,then you need an enamel or lacquer thinner to remove it.It will leave your acrylic gloss coat and base coat alone if they are fully cured and if it truly is acrylic,as you seem to be guessing.
cant think with your finishes,need to be certain.