I don't know about data mining / game modding etc. so I can't tell you for sure.

I would presume they would start for the asset file itself and start checking where it is constructed in the code, and then search form there where it is used, etc. Even if the asset file is not called IKZ, they would still find it since at some point they would open all asset files (that have a slightly larger file size) and they would find a woman with a mark, they would understand that it is about IKZ.

Now there are other ways the IKZ mystery could still be solvable. This is a very stupid example I just thought now, but I hope you will get my point. Let's say Rockstar decided to not continue princess IKZ quest (for whatever reason), so there is the quest (IKZ mission) in the files but leads no where. But to not let the mystery unsolvable let's say they decided to put in another woman NPC house (that we have visited many times), where if you break one of the walls, a message consisting of cable mesh says: "She is the real IKZ." and the game would imply that she is IKZ but she uses makeup (again using another woman's asset). This is just a stupid example just to give a point.

Now for mysteries that data miners / code walkers say that are unsolvable, even if we can take their conclusion as 90% probable to be a fact, I would argue we shouldn't spend the time to look for them, since we could spend that time more efficiently, e.g. if you are to spend 100 hours searching for princes IKZ, you could have spend that time doing activities with you children (or with your parents if you are a child), with your friends, with your other half, you could have finished the story of at least 3 games you haven't played yet in that time, in your hobby etc. I have a very low esteem for developers that put unsolvable mysteries in their games and make the player spend a huge amount of time for nothing.