This new area of the park is looking great!
With a few more trees & shrubs around the lake, combined with some rock ground textures, it will look a "Complete" area.
Coaster wise, it looks great, but needs some adjustments. Some of the elements on the coaster look far to tight in the parts of the layout they are. Usualy in a roller coaster, smaller elements such as an in-line twist, should not be taken at high speed as this causes extreme G-Forces. When the train negotiates an element, it should slow down near the top of an element (such as a corkscrew or loop). With regards to twists, the ones featured in RCT should be taken at no more that about 30mph. Also, coasters should never travel upside down unless in an element. (for instance the two midcourse half corkscrews on this layout, the lead up to them is upside down it too long.
Making some adjustments here & there should easily make this a realistic coaster layout,
Firstly, If yu make the turn after the first drop a larger radius, you should then be able to replace the small corkscrew with a large one, or two diving loops after each other to create an extra large corkscrew.
The two corkscrews after the first turn on the lake you could replace with a zero-g roll if you make the turn on the lake a larger radius.
The corkscrew after the tunnel needs sorting out. At the moment you have it inverted, which as I said before, is not prctical due to G forces on a coaster. An inverted coaster like nemesis is obviously fine, as the train is underneath the track with the riders orientated correctly.
Up until the climb up the hill to the station looks ok, however I would add a brake run at the top of the straight climb. This could easisly be fitted on if the climb is made steeper.
Then you can just use flat curves to connect to the station.
A lot to take in I know, but I'm sure you will get the gist of RCT coaster building with some practise!
I hope this helped, and I look forward to future updates!