Thank you for your application! I would like to give you some tips on what you can do to increase your chances to get accepted.

The Tree is very nice, or it would be with six sided logs. On MCME build server you can get these with '/get logs' command but on single player is probably not possible without modding. So don't worry about this, the tree is well built.

Your Tol-in-Gauroth is a good start. There are some things you should try to improve though.
You made some nice cliffs around, but they would look even better if they would not be only two or three blocks thick (I know there seems to be too little space, but you can to it). Now they look a bit flat. Also they are all roughly of same shape: very steep pinacles. It would be more realistic to have more distinct shapes. You mixed in two addional materials (emerald and coal) which is very good, we usually places them in clusters not single blocks. You may want to try that too. Have a look at some cliffs on the main map for example at Dol Amroth. All the stone looks quite uniform, you could try to add some blocks with more distinct texture, gravel for example at the bottom of the cliffs and the lake floor. Again nice cliffs
You already got the basic wall concept we are using on MCME: Nice pillars and arches in first layer and fill in the walls in the second layer with another material. The two materials should be distincly different. Your choice of stone bricks and cobble for the side towers is already very nice. Those three blocks wide windows are out of MCME style though. The main tower with a mixture of bricks and smooth stone in the main wall layer looks a bit confusing to me. Additionally the distance between the pillars is very large. You could try to add a pillar in the middle.
Also your wall design is quite simple. You could decorate the walls with some stairs and half slabs. For example you could make some nice arches between the pillars.
Your towers look truncated, even unfinished, a fancy battlement on top would be cool.
Next thing are interiors. Your main tower is completely empty. Interiors are very important, make a staircase and some floors and try to to figure out for which purpose every place is used. There are a lot of blocks for decoration (cobweb, rails, levers, hooks, ...) some you can't place yourself, place wool instead with a sign on it which says what you want. Then ask a Designer to replace the wool for you.

When you have more screenshots to show, add them to your post above. When you do, please also reply to this thread. Just say "update" and quickly explain what is new. It will bring your application on top of the long application list and will make us notice your update.

Aside from themed builds you can improve your chances to get Artist by helping with >>jobs and plotbuilds<< as you already do.
Looking forward to your next update