Well, those scripts are vaguely picographic, but I can't see the Matari language as being symbol=word based like that, because languages like that are difficult to learn, and are learned by immersion largely, meaning it would be lost during the years of captivity. There has to be something though.
What it could be is something like Tengwar, which heavily uses Diacritical marks.
I rather like the symbols though, they're interesting, however they're not anything like what we have on earth, the one on the right looks vaguely like Klingon. The one on the left, tbh, looks a bit like Napaanii. We can work with that though.
As for the way it sounds I'd always imagined it to be fairly smooth and pretty sounding, but sort of rough around the edges, like Gaelic, elvish, or maybe Italian, and I know, yes, yes Seri, western influences, blah blah blah, but I'm just giving examples for the way it should sound to speak based on languages I know. If we design it right, it should be its own thing entirely.
Now, thukker and possibly Brutor, I always imagined as being very harsh and vaguely violent sounding. Russian, German, Hungarian, and maybe Icelandic come to mind as examples...oh, and Klingon. Very guttural.
A couple things that would need to be kept in mind when designing either of these languages: These languages were kept alive through 700 years of slavery and culture erasing, so they need to be easily transcribed, and they need to be phonetic. You need to be able to look at a letter and go "this is the sound that this letter makes" no caveats, no exceptions, it needs to be as simple as possible.