You're probably right that having blyxa on both sides will help tie it together. I'm looking forward to seeing how it looks.
My bolbitis grows best when it's in an area with good water flow. It doesn't have to be right in front of the filter outflow, but it does seem to prefer water movement. I occasionally remove older leaves as they can get a bit scruffy looking and accumulate some algae. It's more prone to algae when it's close to the light.
Have you started the moss/epiphyte cube yet or is it a future project? Sounds like great idea.
It's looking good. The stems on the right are a nice balance to the left and they do suit the look of the tank better than the fern. The poof of green front and center is rather distracting. Is it something attached to a rock? I think it would be better suited placed either to one side of the tank or the other and a bit further back from the glass so it isn't pressed up against it. Other than that it's filling in very nicely.