how to assess blend if-settings with javascript

Oh, I absolutely need help with those … thanks for Your indulgence!

What I’m after (and mainly for the challenge, not because I have an actual need for it at the moment) is getting the the same effect as the applied Blend If-settings through masks on a non-blend-if-layer (and I’m aware that they are then no longer »live« so to speak).

Anyway, I was operating under the assumption that one could produce an identical result when resetting the formerly top-layer and putting it below the other one and applying the inversed Underlying-settings as This Layer-settings to the newly top-layer.

Unfortunately that seems to apply only for the Gray-settings, but when the other channels are modified it doesn’t hold true.

So, even if it might not be any help here, I would like to know how I can get the values in a layer’s current settings.

Because when recording an edit with Scripting Listener I get something like:

var idsetd = charIDToTypeID( "setd" );

    var desc58 = new ActionDescriptor();

    var idnull = charIDToTypeID( "null" );

        var ref51 = new ActionReference();

        var idLyr = charIDToTypeID( "Lyr " );

        var idOrdn = charIDToTypeID( "Ordn" );

        var idTrgt = charIDToTypeID( "Trgt" );

        ref51.putEnumerated( idLyr, idOrdn, idTrgt );

    desc58.putReference( idnull, ref51 );

    var idT = charIDToTypeID( "T   " );

        var desc59 = new ActionDescriptor();

        var idBlnd = charIDToTypeID( "Blnd" );

            var list20 = new ActionList();

                var desc60 = new ActionDescriptor();

                var idChnl = charIDToTypeID( "Chnl" );

                    var ref52 = new ActionReference();

                    var idChnl = charIDToTypeID( "Chnl" );

                    var idChnl = charIDToTypeID( "Chnl" );

                    var idGry = charIDToTypeID( "Gry " );

                    ref52.putEnumerated( idChnl, idChnl, idGry );

                desc60.putReference( idChnl, ref52 );

                var idSrcB = charIDToTypeID( "SrcB" );

                desc60.putInteger( idSrcB, 0 );

                var idSrcl = charIDToTypeID( "Srcl" );

                desc60.putInteger( idSrcl, 0 );

                var idSrcW = charIDToTypeID( "SrcW" );

                desc60.putInteger( idSrcW, 255 );

                var idSrcm = charIDToTypeID( "Srcm" );

                desc60.putInteger( idSrcm, 255 );

etc.

with the values for all the handles.

But how can I access those numbers from within a Script, for example to apply only certain ones of them to another layer?