Afrikaans dictionaries are very welcome.
However, >95% of members of FreeMDict are from China and there is little interest for Afrikaans among them.
I am afraid that if you really want to use those AFrikaans Dictionaries in GoldenDict, someone really interested in the language would need to crack the .exe files to make a .dsl/.mdx file.
It is extremely unlikely that it would be done by Chinese members of this forum. You can try by yourself. The chance is higher than waiting for others….
If you crack the database, then it would be easy to make a .dsl dictionary