I'd attach some of the java fern on the side of the wood for sure.
I'd stick the lotus in front of the filter where it will make a nice centerpiece plant, and the crypts around the front of it and the wood sort of scattered naturally where they won't mind the shade from the lotus leaves (unless you plan to keep it very very short). The val will spread a lot unless you pinch back runners pretty ruthlessly, and will also bend and shade stuff nearby, so take that into account as well. The crypts will like the shade, but will make it very hard to tend runners if planted too close. I'd use a rock to glue a java fern as a way of planting near the val since it can be easily moved and replaced, and will take the lower light.