Welcome back to the Wefugees Community and thank you for your question.
If someone with a residence permit according to par. 25 (2) of the German Residence Act (refugee according to the Geneva Refugee Convention or someone with Subsidiary Protection) is applying for family reunification, the family mebers usually don't need to prove German language skills. The BAMF published a brochure providing a good overview who under which circumstances is actually in need to prove German skills and other useful information (in various langauages).
I hope this helps and all the best,