Ok, tested in Spanish language AE. Here are results for future reference and anyone interested:
// English version (breaks in Spanish AE)
comp("Comp 1").layer("myLayer")("Effects")("myCtrl 1")("Slider")
// Spanish version
comp("Comp 1").layer("myLayer").effect("myCtrl 1")("Deslizador")
// Works
comp("Comp 1").layer("myLayer").effect("myCtrl 1")(1)
// Also works
comp("Comp 1").layer("myLayer")("ADBE Effect Parade")("myCtrl 1")("ADBE Slider Control-0001")