Been away for a couple of days, so I couldn’t comment further on this. I downloaded your file and took a look at it. But first, lemme comment on this:
Sure copying the bone layers code and changing names doesn’t do anything, that’s to be expected. Controlling the visibility of bone layers is controlling blender’s UI. Shapekeys are part of the mesh object, not blender’s UI, so it’s two different things. Like apples and oranges, yea sure, they both grow on a tree, but that’s pretty much the only thing they have in common. Also, there are no bugs in blender in this area, there have been changes in the API that would cause older files to not work in current releases, but a few changes to an older script will bring it up to date with current release.
Looking thru your file, I noticed that some of the shapekeys have drivers on them that are controlled by bones. Since the mesh came from DAZ, I’m assuming the rigging work you’ve done yourself in blender. So I’m also assuming that you’ve set up the drivers to control the shapekeys and linked those drivers to bones yourself. If you’ve done all this work yourself, then really you’re half way there…
If you can control a shapekey with a bone, then start from there and take baby steps to accomplish what you want. Here, follow these steps:
Take another look at the file I posted, delete the text file from it, save it under another name, and quit blender. Now restart blender and load in the file you just saved. In the 3d view, in the transform panel (right side of the 3d view) you should see under ‘properties’ a box that says ‘wide’ and has a slider. You have to be able to create that before you move into python. As I said before, the only thing python ads to this is a nicer, custom UI. This is your starting point.
So, start a new blender session, with the default cube and add a shapekey to the default cube. Now add a single bone armature. Now, here again, I assuming you know how to drive that shapekey with the bone, as your file shows me. If I am incorrect, then we have to back up a few steps, got to have a good foundation to build a house. Anyhow, instead of using the bone to drive the shapekey, you want to use a custom property of that bone to drive the shapekey.
Have you watched the video I posted a link to? At about the 7 min point, I show how to add a custom property to a bone in pose mode and use it to drive a shapekey. This will give you the same results as you have if you followed the steps above that I mentioned to do with my example file. You have to achieve this before you can think of using python.
Hope this helps, and I’ll be AFK for a few days… but I’ll check back,
Randy