I think there is something wrong with the implementation of the translucent water plane from the learning library (at least for 4.10). I was able to get a translucent material to render a foreground object using SSR though so I will make my own shader. I will also try 4.11.
I appreciate your caution about performance but realize there are other applications for the engine other than games. I am using it for a fast render-to-video project where even 0.5 FPS is a huge win over alternative (although more accurate) renderers.