it has been a very long time since i used acrylic enamel so i don't know if i am accurate.
there used to be acrylic enamel reducer and urethane reducer, and there probably still is. the urethane reducer is has MUCH stronger solvents in it. when you use it over properly stripped and primed surfaces you shouldn't have any problems using urethane reducer. when you use it over older surfaces it may bite into the under coats and cause lifting.