I don't know about Aerad but do know a bit about Jeppesen, having been involved with them for many years. First point is that, when they reproduce a States' charts in their own format, they depend on the data from the State being correct. If it is wrong, their chart will be wrong, simple as that, Of course, they are usually very quick to correct errors when notified.
Jepps have quite a large commercial procedure design office in Atlanta. They do contract work for anyone who wants it - using TERPs or Pans Ops, as dictated by the customer. They also prepare complete AIP to order. I feel sure that they carry a LOT of insurance for this work and am equally sure that it's included in the prices they charge for these services.
I guess that Aerad probably does much the same thing.