A common problem with this script is the following:
In the shots, you can see, that the bcp goes to a wrong background node.
Would it be possible for the script to simply take the next item in the sequence? Or is that what it does and it doesn’t work properly here? Could I do anything, to make it work? (background has the same order as foreground.)
I use Mask To Master from the Freemix tools for this purpose, it works very well.
What Jens says. It is the ultimate tool (a million thanks to Florian for pointing it out here two years ago or so).
This use case is beyond the purpose of this script. The two drawings are just too different.
How would the script know which sequence is correct, and which is wrong? How would the script determine any sequence in the first place?
It aligns each point in the foreground to the nearest point in the background.
Tim’s Mask to Master handles this very well 
The purposes of the scripts are simply different. Align doesn’t assume correspondence to points in the background, it just takes the nearest positions.
I cannot find »Mask To Master« in the Freemix scripts, but it seems to me that »Adopt Background« does exactly the same thing. Is that the script you are referring to, and has it just been renamed?
Yes, the script has been renamed.
