Unfortunately, this is one of the major limitations of Photoshop Touch.
All "effects" you apply to layers are permanent. Meaning these effects cannot be edited later on, at any time. That includes even if you open the .PSDX (Photoshop Touch file) on a regular Photoshop desktop version.
There is also no way or sign for you to know if a layer has had any effect applied to it.
Sorry for the bad news. Hope this helps.