I do not know if this would help anyone. CAD file for the No 5 flash hider.
No. 5 Jungle Carbine Enfield Flash Hider CAD File | KommandoPost.com | KPS Militaria Collection
Could the FH not be produced with 3D printing?
The repro is not completely useless. A little added QC would make them at least an acceptable band-aid.