I would chuckle at this too but with my experience and your scripting magic I do not kow what is real and what is not. Does Vilja track strawberries? I think I ever only see one in her inventory. I do not recall if she carries sweetcake and sweetrolls but I would guess not.
Putting things in her inventory doe snot do anything other than make her use them (in case of weapons and armor and torches), correct? So if I put ingredients in her inventory it does not mean she will recognize them (at least the forst two effects as she is static at her alchemy level)?
My assumption is that if something is not done through the dialog level then it will have no affect on her disposition.
Same if I give her a robe that adds +50 to alchemy, she will not be an expert, but is static.
Also, one more question. I use Wrye Leveling, where I pay for level ups instead of using my skills. I then manually distribute my skill points. I have done this in my last test game and notice that only Vilja sneak skill matches mine, her other skills are in the 30s even though I am level 22. How can I make her catch up? Will she only do this through skill use and will they be accelerated?
No we haven't added anything to track strawberries, but that's a nice idea. She'll use anything in her main inventory (but not the red and blue containers) like any other NPC. That typically means she'll equip the best (most expensive or most effective) clothing, armor, and weapons. She'll also eat food and drink potions if the situation calls for it and I've never tested but she'll probably use spell scrolls too.
Disposition changes are mainly through dialog, but like all NPCs her disposition toward you will drop when you draw your weapon, accidentally hit her or other friendly creature/NPC, have a disease, etc. Most of those are temporary changes, but I don't recommend hitting her or Bruse.
Enchanted robes will work for most skills but there are a few skills that Vilja (and most NPCs) don't use. I wouldn't waste your time giving her a boost to Alchemy, Armorer, Security, Speechcraft, or Mercantile. She either doesn't use or gets such a small benefit from those skills that it's really not worth it. Her "alchemy" abilities are static because Emma had to create them through dialog. NPCs can't really make potions like the player. (They also don't pick locks or repair armor.)
The game adjusts Vilja's level to match the player. There must be something about the way that Wrye Leveling changes your level that keeps the game from updating her skills. Are you sure you're level 22 according to the game's mechanics? Have you been sleeping regularly? I'm not sure exactly what even triggers Vilja's level change because the question hasn't come up before and I know that other people are using alternate leveling systems.