Hi,
After a suggestion of @nhedgehog to use Wiktionary XML source files and to extract more content, I looked at this format closer and I was very astonished that they do not use xml tags to delimit sections (e.g. synonym). Overall, the structure is quite a loosy...
So it will be a huge work to satisfy the wish of @nhedgehog (and probably others too) from scratch, but I also looked at the source file of this project:
https://github.com/BoboTiG/ebook-reader-dict which makes a grat work in parsing and generate a stardict format file as output. I think it would be not too difficult to add code to extract more content. I also think that it should not be too difficult to add XDXF output format for our PocketBook reader.