Level Artist tasks really depends of the company itself. Imo, LA don't do models and textures, wich is the tasks of an Environment Artist, but build the levels from LD's sketch to final debugging.
In some companies, LD and LA make the layout of the map together.
You need to push the visual of your map, makes all the details and lighting (except if the company has Lighting Artist) but you also need to collaborate with Level Designers to make sure visual and gameplay go to the same direction and also make sure that LD's don't make crazy "unartable" things.
It's also full of technical constraint, you are the one who need to check collisions, navigation, framerate, etc... as you are the guy who take cares of the map.
I'm a level Artist and I'm a shitty texture and model maker (I means I have some great skills for a PS2 game :D) and also I can't draw a shit !!!
Aha I felt in love with Skellige ! I still didn't seen the country side of Kaer Moren but yeah Skellige is fucking awesome. The landscape, the music, the villages, the castles,... This part of the game is escaping me of the reality.
Thank for that !