Wuk could have worked if they played heavily into her being very, very sheltered and needing advise by the WoL how to handle setbacks. From ARR to EW both WoL and Scions had to deal with many, many setbacks, put Wuk in similar but less world ending situations and when she falls and is hurt, WoL-Senpai is there to spit some wisdom and grow.
Wuk generally couldn't have worked (and this story generally doesn't work) because your main character, while talented at many things, has no experience running a nation. Generally speaking when this comes up prior - the character you're working with already has a mentor (Nanamo has Raubahn, Manderville, and even Teledji. Aymeric has the lords, including Edmond. Hein has Gotestsu and company. Lyse has Raubahn and Conrad and so on).
The story would have taken a massive shift for the better if Wuk was instead Captain of the Vowsguard for Koana and you could mentor her about that instead. You could much tie in plot points from your WoL that would directly impact her and still keep many of the same themes (aka having to come to blows with her brother) ultimately ending with her being
effectively being the second Vow (without literally doing it). You could have several scenes where you're talking to her about grappling with difficult concepts as, effectively, a soldier.
There's tons of wasted potential as there are several things you could just have be a scene with her that would really give the player the chance to contextualize their past. Talking to her about how it felt dealing with Gaius (a man driven by vision and conquest) and relate it to her brother (a man driven by vision and conquest) or even fucking having Gaius tag in for a bit. You could relate about how it was when Minfilia disappeared/died/raptured and how the Scions fared with Alphinaud essentially in the leader's spot.
Essentially your character has years worth of stories and lessons to give Wuk, but you actually give her 0 of them and have very little insight into what it's like to be a nation leader.
It would also be neat if they leaned into the "mentor" concept a bit more and gave you some agency to actually influence
how Wuk Lamat fights. You could have the role quests just be mentor quests where it's you showing Wuk a different way of fighting - even if she doesn't stick with it she should know how it works. Her army isn't just full of Warriors - there's going to be healers, melee fighters, gunners and archers, and spell casters. You could even go a step further and tie each one to one of the lands that Wuk has to learn about and/or tie it to specific characters. Melee could focus on her as a Viper (like her brother is and father was), Ranged pDPS could be tied to Koana, and so on. Have her learn how to craft things and tie it to the Pelupelu - have a fun fishing adventuer, etc.
There's a myriad of things they could have done but they really just had kind of a loose concept and ran with it. But in the end you don't really mentor Wuk - she's already is firmly established in her mindset, character, and actions before you show up and you're just kind of along for the ride. Ironically it seems like Thancred/Urianger actually do a better job of mentoring Koana as there's a few scenes of them teaching him lessons and him changing his worldview as a result.