Is there a way to locate an item that is somewhere already seen by you in a part of discovered map? Through debug maybe?
Currently no in-game way.
You can search the saves for item’s ID, though.
Yeah I mean I’ve done this a few times. You need a good text editor like notepad++, and a search program that can search for text inside all the files in a given folder. I used a program called Effective File Search. You open the EFS, and set it to search through the ‘save’ folder using the item ID (make sure it’s set to search INSIDE the files). Though first you may have to look up the item’s ID. I once looked for a gunsmith repair kit, so I set EFS to search for ‘gunsmith’ throughout the entire game folder, just to find its ID. Anyway, depending how rare or common the item is, you might get several map files as result, and they’ll all contain the said item, possibly even multiple times. You then open a map file with notepad++ and search it for the item ID. With some reading effort, you will then find the item’s coordinates somewhere in the vicinity, which are up to you to decipher. Essentially it’s like xyz type of thing. My memory gets hazy at that point, because I don’t remember how the coordinates were presented.
I can’t remember the process fully but it’s sort of straightforward, although there might be some learning curve if you haven’t eyed through the game’s item files before, and therefore don’t know how they’re organized. You also have to know how the map coordinates work. In the game, if you view the map, your current coordinates are at bottom left. You’ll get a hang of it. You can figure out a lot in a few minutes.
Some time ago NPCs were unable to follow the player through stairs, so I used this same process to “teleport” NPCs up from the lab depths to the surface (in a lab start scenario).
So believe me, it CAN be done 
What if the item is an artifat with is generated randomly. Is that possible as well?
Long time lurker, first time poster, obligatory Thanks for all your hard work!, but my nerd sense is tingling:
N++ actually includes this functionality, no need to use another program. Spoilering images, step 1 is to CTRL+F in N++ to open the find dialog and the Find in Files tab:
Step 2, specify your search term and directory, or the little […] box to browse to it (and be sure ‘In all sub-folders’ is ticked):
Step 3, check your results at the bottom of the window, it returns the whole line found and in which file, allowing you to just click the line or file to open it in the editor.
N++ is neato like that. Sorry Lesseps, no idea about artifacts. =(
Windows search itself can find in file…don’t even need N++.
And if you really want to specialize then use http://www.wingrep.com/
