There are a couple of things here which define the color:

In the under surface you you drive a color map into a node which also has a color (diffuse map). The 2 colors are multiplied - making it darker

The other thing is the specular node. This one is the color of the texture - so make it a bit less dark in the specular places.

The third one here is the color in the translucence channel - this color is added to the colors present, this makes it a bit less dark as well (every bit is added, so even adding a very dark blue adds more light to the pixel). The translucence value defines how strong this effect is.

So you have to manipulate those values and colors to get the color you want. I can't be of much help here since I have no idea what purple or lilac is (in terms of color)

 

The under surface does not have glass like behaviour. It is just transparent. The transparence map is translated to a greyscale and then multipled by the transparency value - so the grey area is half strenght in this case. Making it all not very transparent. If you want it the be glass, do the same trick as in the upper one (using the edgeblend, reflect and refract nodes with the transmap modifier for non transparent areas). But I am not clear what the under surface really is (the mesh), so not sure if you want this

 

The setup in the material room for the upper part looks fine. All nodes are connected where they should

 

Hope this helps a bit