That's a great start! Yes, when things fill in it will come together.
I agree, my crypt wendtii also gets leggy and spread out, so I consider it a midground plant most of the time. I do have some shorter ones that I use in a nice, big clump that is perfect for the foreground, so I guess it depends on your source for the crypt.
I have never scaped a tank this shape before, but plenty of folks do a fantastic job aquascaping fluval edges, so I think you have plenty of inspiration available to you.
I'm not sure what the focal point of this tank is supposed to be? My eyes are going to the crypt wendtii, which are right smack in the center. My eyes are also competing with the stones and tiger lotus in the front left corner, for the focal point. That makes me confused and dizzy
Perhaps move the stones to where you want the focal point to be? The stones are the brightest color and also the most constrasting color in the tank, so my eyes go to that very quickly.
Creating depth is a great way to make the tank appear larger, and more 3d. The placement of the wood in the forground, going horizontally, kind of cuts the tank or cuts my depth perception. I can't see what's behind it, and it makes the tank appear less deep. Placing the wood at an angle, with the tallest part behind and the lowest part in front, can add depth.... I have no idea if that makes sense (~_~)
The anubias are pretty spread out, I find my eyes wishing they were all in one group. In dutch aquascapes you see that plants are all in one clump if they are the same species. When the same leaf type/species/color are spread out, it doesn't look as tidy.
Also, be careful when burying the anubias in the substrate. As you know, don't bury the rhizome. Even so, my anubias always do poorly when buried! They do much better with the roots floating in the water, or against wood.
You have a lot of other plant options to fill in your tank. All of my tanks are either low light or SUPER low light, and all my tanks are full of plants.
I highly recommend you try java fern- it looks great, especially if the plant is big and healthy. It also has different leaf shape and color, so it will add a different spice to the soup, so to speak.
Wisteria is also an option- I have a ton. It does look weedy in low light, but it also has a very interesting, fingery leaf shape. If pruned often, it looks nice.
You may also want to try water sprite, I think it would grow without a problem in this amount of light.
Rotala indica is another.
Najas grass, left floating or rooted, is also fine in low light.
Vals also are great- since your tank is tall, vals are a good option. Choose a thinner-leaved val, like italian val, since your tank strikes me as small. Jungle val would be too wide-leaved, I think.
Various crypts, and various anubias are also options. Dwarf sag too, of course. And don't forget the moss! Now that I think of it, I'm surprised there is no moss in a this low light set up
Moss and low light go great together.
