I haven't had luck with CA and ply either.
Last year, I had a profile with an OS 70 4-stroke that the area ahead of the leading edge started to delaminate from engine vibration, a common profile complaint. I pried it apart a bit, dropped some microballoons and medium CA in and clamped it quick. It still came apart.

I'm probably going to add 1/8 bolsters on the sides and pin with several dowels. I hate to add the weight, but the other option is to 'bin it', as the Brits would say.