It's certainly possible, I think it's quite simple if you understand how the mechanisms work in Terraria. In general, you'd need some experience with Construct 2 first, make smaller things to get used to Construct 2, and probably best to have a lot of experience with Arrays.
The tiles system would be somewhat easy as long as you have the knowledge about Arrays, optimising, ect. When a tile is made, you just have it check next to itself in each direction to see what tile is there, then you can set it's frame to what it should look like (Middle block, leftwall block, rightwall block, block with grass on it that connects to the left, there's a few lol)
Having the different biomes that spread slowly is possible, but again, optimisation: You can't have it constantly checking to spread the hallowed area into the grass every moment for the entire world ;)
Movement and fighting is very simple, definately nothing compared to the tiles and stuff.
Lighting should be comparably easy to the tiles system, probably involves some sort of pathfinding, though I don't think the pathfinder behaviour is currently a good idea AS it currently can't just "Pathfind" a certain section, meaning bad lag. Though another thread suggested for a "specific area" thing so you can just search around the area of a light source, say a torch, to light up around it rather than the entire screen.
Inventories, items, crafting, building, it's all arrays arrays arrrraaayyyys (and some WebStorage if you want peoples creations and characters to be saved :P )
Online multiplayer is always the talk of the Construct 2 forums, it's possible now, but lacks proper support (til the future perhaps).
Enemy AI in Terraria is simple in terms of AI mechanics; a slime enemy just jumps in the direction of a player every 2 seconds or so, with some extra factors involved to make it jump sooner. Bosses have a small pattern, there's no advanced difficult pathfinding algorithm involved, just "Go to player, kill player."
All in all, the tiles system is what makes Terraria, nobody was impressed by it's battle system, it's all about the tiles, and the tiles would be the most time consuming thing to create, which might be why there's no immediate tutorials around here (I haven't searched myself).
Getting it to run smoothly and lag-free, that's the challenge (unless you have the knowledge on how to optimise very well, then again, easy)
It's all about your knowledge, Construct 2 is extremely powerful as long as it's 2D!
I think there might be some interesting stuff and tutorials if you search on forums, I don't have anything to help other than my opinion :(
Hope this helped!