Seeing as the full version has yet to be released, I'm confident that you can rewrite his dialogue so that the only prominent African character is not also the only one that speaks like a very bad online translator. Seriously. People calling him Q is fine. Having him be quiet because he's not confident in his mastery of the language is fine. Having some grammar errors is also fine. WHAT YOU WROTE IS FRANKLY RACIST.

If you don't want to do the work, I will HAPPILY rewrite it for you. And for free! Just please God either cut the racism or let me do it.

So, I'm guessing your main character isn't black? Because she'd be way more prominent than Q. I'm also completely confused by how Q being black is racist? And keep in mind your only seeing the demo. So Q and the bard (Who is a mini-route) and the main character are likely not the only black characters in this game.

For the record I clicked on this post because I actually like Q a lot and find him to be one of the more interesting characters. He seems to be extremely vigilant and serious and I'm excited to learn more about him as the story progresses. He's a great counterpart to his partner who seems to be the comedic relief and is somewhat of a clown. ...Like the friendly version of Terian who is also somewhat of a clown. MY hope is that we get a closer look at all these side-characters and not just the LIs. And no. I don't want them to rewrite his character. I'd rather just have them change his skin color if it bothers you or anyone else that much. He's interesting just as he's written.

Even if we ignore that the future queen could be any color, Q still isn't even the most prominent dark-skinned character we've met so far: Lliria is. We don't know as much about her yet, but she's definitely very clever, well-spoken, kind, and immaculately put-together. 

Also, where is this notion that Q is "fierce" and "barbaric" coming from? It's possible that he could be fierce, but we haven't seen anything but calmness from him so far. He seems competent and alert and very self-controlled, not "barbaric" in any way. He is certainly strong, but that's not necessarily a racial stereotype, and any of her guards would have to be strong. He doesn't speak fluently, but the text makes it clear that that's because he's new to the area, not because he's unintelligent in any way. 

It's important to be aware of racist or racially insensitive characters, but Q very clearly isn't one.

The human mind is very good at seeing what it wants to see (especially when we are looking for something specific) and we often look for racism. This is a good thing! It helps us avoid in in situations where it could have been ignored. Unfortunately it can lead us to mistruths some of the time. Personally, I felt Q was vigilant, serious, and trustworthy. I never got a barbaric or unintelligent vibe from him but more of a stoic vibe, which I hadn't really second-guessed. In my mind, he was silent because he was more concerned with doing his job well and keeping a constant eye on the situation than learning/speaking the language. Not because he wasn't smart enough to, but because he had other priorities. Plus, having someone you trust around to sort of "translate" or fill in the blanks for you often leads to quieter people. Children with older siblings do this often, and won't learn to speak until later on.
*shrug*
It really is a matter of perspective from the reader though, and just because one person sees something one way doesn't mean everyone does, or that everyone has to.