I apologize for having caused this hassle. I wish I knew there was a moodle XML format, and that it was possibile to export the samples in that format. When I described what I would have attached I did it exactly on purpose to check if the file formats I was providing were suited for the needs. Obviously some misunderstanding occurred in between posts.
Similarly, I wasn't aware of the 0-100% threshold of the question testing tool, is it mentioned somewhere in the documentation of the tool? That obviously explains why I am not getting the intermediate scores proportionally represented in the computed scores column.
As for the overall negative result in matching rules and answers I provided, I cannot really explain why, when tried individually they worked.
I attach a .zip file with the screenshots of the results from each attempt, in case you wanted to compare. Files are .gif or it would have been too large.
However, many thanks anyway for the time spent trying to fix my problem.