Usually these kind of startups that produce native libraries for use in other software produce poor .NET libraries. (see sendgrid) I wouldn't place the blame totally on them - you often have 1 person supporting multiple libraries in multiple languages, and .NET is not often used at these sorts of startups. On the other hand, a few thousand dollars for a consultant to get their situation in order would not be a bad investment to get them out of the situation, because a bad experience like this festers in the community for years.