Currently there is a https://www.freshports.org/cad/netgen and it is one major version behind the current 6.2 https://github.com/NGSolve/netgen/releases/tag/v6.2.1810 The logic for creating a 2nd port is becuase there are still other ports that haven't updated to netgen6 AFAICT.
If you make the port, I'll test it and commit it. If you want me to make the port, I'm very busy right now.
(In reply to Stephen Montgomery-Smith from comment #1) Yes, please make the port when it is convenient. Thank you!
Closing this as there has been no progress for years and it's not a bug
To be more precise, main port (cad/netgen) was updated to 6.2 in commit 4d678ffe697be8a0cb81583507bd697d74785bf7