To address your points:
1. This is a moot point when you realize that we're playing a video game, not watching a movie or TV series. We're not playing as Wuk Lamat, we're playing as the Warrior of Light, y'know, strongest warrior in the lands, savior of the star. Yes we're treated as a threat by some NPCs but the issue more arises that we're essentially a prop for most of the story, which by itself isn't a bad thing if MSQ wasn't 95% cutscene and 5% actual gameplay of varying quality.
You mention that we're supposed to be a mentor to Wuk Lamat but she just genuinely isn't curious about us or the scions who are almost as extraordinary, she just goes back to "Peace, Unity, Work Together, Understanding" when something she doesn't understand is mentioned.
Wuk Lamat is supposed to be curious about cultures and strive to understand others, why does this not extend to the scions and WoL around her that are helping her?
2. I'm not going to address this because honestly I didn't particularly notice the voice acting, I just know that it's probably not the VA's fault if she doesn't put the appropriate emotion into scenes since, like in the trial, the voice lines with no context can be interpreted in a more neutral tone instead of in the middle of a battle, and I think it's likely she was given the lines without being told the context
3. Wuk Lamat didn't develop as a character, nothing changed about her from the start of DT to the end except maybe her confidence level and how strong she is, but these two things are honestly not compelling in terms of writing a character. When you set up a character you need to give them some sort of struggle and a catalyst that causes them to grow or change in one way or another. Zarool Ja is a perfect example since he basically ended up slowly spiraling into becoming a villain because of his ruthless nature and boundless ambition. He had a great character arc and it's a shame Wuk Lamat didn't undergo something similar but in the opposite direction.
4. I'm okay with her being in the 2nd half of the story, but she should have been shoved out of the spotlight to give Krile, Erenville, the WoL, and the other such characters more time to shine. It makes sense for her to be in the spotlight in the first part because she's a trial participant and we're here to help her, but dealing with invading forces from another shard is kind of a scion job.