I'm never in favour of gluing anything, especially when its likely to be subject to water immersion. I just don't trust glues due to experience. With any glue the bond is always great right up until the point it fails
I use araldite purely as a sealing agent that also strengthens the area / join. The barbs are held in by the thread pitch not the bond of the glue. About the only glue I accept as good enough on its' own is used to melt plastics together, like model kits or plumbing pipes for instance, but thats more like plastic soldering than gluing. Anyway I don't think this would work because the body of the unit is a resin based. What size / type of barb would you need in it anyway?