I am not quite following,if you used acrylic paint the fluid should be okay,but panel lines are helped by a gloss coat,helps to flow easier.Make sure coats are completely cured.
To be sure,you can test the effects of your wash on painted scrap plastic or plastic spoons to see what happens.
Rule of thumb: acrylic base= enamel,oil,or lacquer washes
You cant use acrylic thinner with lacquer paints,try commercial hardware store lacquer thinner
Hope this helps
Any other basecoat,use acrylic based wash
Or make sure you use clear acrylic base.