Welcome to the forum Edville. Haibike makes some great bikes. Regarding your question, there isn't any special training involved in being a Haibike dealer, however some dealers are trained on the specific motor systems, in Haibike's case Bosch or Yamaha and now TransX with their new Urban Plus model. Beyond that it's pretty standard bike parts. That being said you'll want to work with a competent dealer with a good track record.
I hope this is helpful. Feel free to reach out if you have further questions.