Hi Fu Bo,
Jentrata/Hermes implements a number of very mature B2B messaging standard which have been around for close to 20 years and have reached feature maturity from a protocol perspective.
Jentrata has been running in production with a number of large deployments globally for many years without any major issues.
I am the first to admit Jentrata lacks documentation and this is something that is being worked on albeit slowly. The community for open source B2B gateways is pretty small so am always open to some help improving documentation.
If you have any specific questions about setup or configuration please let me know
cheers
Aaron