From an objective standpoint, Ms. Light's courtroom debut in Turnabout Siblings is honestly a pretty solid case, especially since this is your first (?) attempt at making one. You have an OC protagonist with a unique personality. You have custom graphics for both characters and those screenshots that no one actually makes because they're damn hard. You have a game that has very few "dick-move" moments with logic that can be followed, and of course you have the obligatory colourful cast and custom music. My opinions on The Confessed Turnabout (so far) are mostly the same.
After playing through TSiblings in its entirety, my personal opinion on this case is "It's okay". I obviously don't have as much of a problem with it that Enthalpy did (and I don't know how much of an issue he's got now, after the re-release), but I am definitely not going to shower this work in praise as seems to be the common reaction. As you'll see, I like the second installment much better.
I'm going to do this in two sections. In this first one, I'm going to look at both cases as games, as well the plot and general construction of the works (since tCT isn't finished, I'm going to talk mostly about TS), and in the second, I'm going to look at the cases as stories, including writing and characterization.
TSiblings is obviously not that long, being two parts and one trial segment. Clearly this was meant to introduce the main characters to the reader and act as an obligatory tutorial type case since it is the first in a series. As such, the crime was fairly simple, as was figuring out who the murderer was. In terms of gameplay, it wasn't too difficult, but as always there are some tricky spots. There were two spots when I needed the walkthrough. I totally missed Oldbag's missing patrol, which was my bad. Then there was that ladder contradiction. I still don't know what the hell Angela's argument was there. Something like, the ladder wasn't leaning against the fall because it was a stepladder which has supports? I have no idea. Aside from that, there was no points in particular that were super rough on the player, which is commendable for a first case. I also had no problems with what there is of The Confessed Turnabout.
Basically, I have two major critiques about Turnabout Siblings' plot and coherence. Firstly, it's just not that interesting. Subjectively. There's never any moments that really impact the player, or if there were, I have already forgotten them. Throughout the case, Angela just sorta...stomps Payne, makes arguments that get accepted and generally gets her way. At the last testimony, I recognize that you tried to up the ante with Dark messing with Angela, but the whole affair felt forced to me. The case progresses in a predictable manner, with the first witness lying for some reason, the locked room not really being locked, the presence of a third person becoming known - it's all pretty straightforward.
The other point I'd like to make is that it feels like a fancase. You probably don't know what I mean by that, so let me give you a few examples. The murder took place in a highschool with an extensive security system and two guards. A literature teacher died after falling onto a ladder while repairing an AC unit when he grabbed a cord from a suspended light fixture which broke and fell on him, electrocuting him to death when the killer flipped the light switch. Both of these things are kinda fantastical and also just kinda...happen. You can tell that certain plot points were devised before the story began to take shape, and which ones were used to fill the gaps between the already made parts...If that makes sense. And don't get me wrong, that's how stories are made - I just felt there were times where the plot was being forced a certain way to have the murder set-up work, even if it doesn't make a lot of sense in context (see above examples). To be fair, this is a really easy thing to get sucked into, and I've seen it in more acclaimed cases too, like Turnabout Bloodlines and whatever was up with the retractable pillar things that held up the court gallery or something...? Maybe that's wrong; it's been a while. For what it's worth, tCT has not had any moments where I felt this was the case. In fact, I think it's a very compelling homicide (Don't read into that.) that makes contextual sense and is interesting to the player. Also more interesting is the tension in the courtroom, which as I said, basically didn't exist in TSiblings. Clearly, your case-making mechanics have improved. Kudos.
And that brings me to the second section. I will not mince words here: the grammar and syntax are bad. The only person I've seen actually comment on the quality of the writing is Bad Player, which I think is astonishing because that is what is holding Angela Light back more than anything else. I'm a dick for saying this, but the biggest twist in the series was when I finished TSiblings and saw that there were, like, four proofreaders. (Not that I'm calling anyone out here - I don't know what they were proofreading for.) Now I think English isn't your first language, based on the consistency of the grammatical errors, everyone saying "lessons" and "toilet", and Room 101 being on the 2nd floor (which I think is a European thing). (If English is your first language, then I am a huge ass and I apologize.) Now please recall that the second thing I said I this post is that I nitpick, but the dialogue in Angela Light is horribly distracting, and I refuse to believe that no one minds except for BP and myself. I feel like 4/5 frames have something off about them in terms of typos, grammar, or syntax. Let me be clear - what the characters are saying does get through to the reader. There are a few times when I was like: "What the hell did they just say?", but for the most part the information is conveyed adequately. But the dialogue itself comes off as being super awkward. I can honestly say that there is a lot of improvement in Part 1 of tCT, but then it falls off again in Part 2. (Although, I'm not sure how much of that is due to it not being proofread.)
Now I could talk about this all day, but I'll get to the point. The awkward dialogue and poor technical skills don't hamper the reader all too much in the way of following plotlines or character motivations, but they do make it seriously difficult to get invested in either. That's a really big problem, obviously since it's the foundation of the reader's enjoyment, and also because when I'm clicking through conversations that I just don't care about, I'll often miss an important reveal or question which I'm then prompted to answer. Maybe that's just me.
So to summarize, Turnabout Siblings was bland overall, was executed surprising well, but suffered from really bad dialogue. The Confessed Turnabout has a legit cool premise, has so far been executed well, and has slightly better writing. Clearly, you're improving, and you didn't need my feedback here to do so. In that regard, I have high hopes for the future of this series. But I feel like I need to recommend that you take steps to improve your writing skills. As always, the best advice you can get for stuff like this is to just read more. Just pick up a book and read it. Don't even analyze anything about it - just read. You more you familiarize yourself with the way conversations flow in a narrative and what does and doesn't make sense in sentence structure, the more you will see it come through in your own writing. For a more immediate solution, maybe grab someone here that knows what their doing and get them to be your editor or coach or something. Maybe ask your proofreaders to be more thorough (if you get any next time). Basically, Angela Light is pretty good at being a game, but if you want this series to really stand out, focus on improving your writing and make the novel aspect stand out. It will do wonders.