Why exactly did Yamashino want to ruin Trucy's and the whole Gramarye family's reputation? Sure, they did cause him to lose his job as a magician but now he's the host of a rather well known TV Show, isn't he?

dude carried a grudge, i guess

Yep, he had a very warped sense of pride in his magic tricks.

One part of the explanation has to do with the fact that black locks appear when someone is mentally unstable basically or weak and about to break and breaking the locks forcefully can damage their soul (fits Kristoph) and the other part is about how it appears when people are unconsciously hiding a secret. That secret is very clear and definitive for Athena: She's blocking out a memory from post-traumatic stress but Kristoph isn't necessarily hiding any particular fact other than that he's insane and obsessed and he's not conscious of it; he's hiding that there is no rational rhyme or reason why he's been murdering his victims.

The black locks were definitely meant to show simply that there's a void of darkness inside Kristoph and the things he hides are irrational (I think) but with Athena they explained it by fitting the Black locks to her situation and then also generalizing them as being barriers for the mentally ill, and while I do think it cheapens what I felt they represented for Kristoph (mystery for the most part) I am okay with the way it's explained overall.

Which one is more fanservice, Maya or Edgeworth?

So... I know Pearl shows up but... what does she actually do for Apollo to perceive her?

She made a promise to the archaeologist to not tell anyone about where he had gone.

Did Trucy know that Kiki existed? Meaning like, did she know that the sisters did a twin-swap trick?

Does Edgeworth have trouble asking for a witness's name?

It's some of those things that build up for a good while through the game, so not exactly "brain melting" material. Maybe I'll give it a 3. Imo, I think it was still presented in a good way, though slightly disappointing in other ways. It's surprising, though, since some of it seems to come out of nowhere.

Someone commented "I wonder what Kiki's name is going to be" which led to me going, "I don't remember a Kiki in AA" which led to Googling, which led to me discovering Kiki Nanano. I didn't spoil any details, I just know the name. But since I already know that Mimi's last name is Nanano, I assume there's a connection. How big of a twist did I just spoil for myself?

So damn close, I went all this time without a single spoiler.

Do Apollo & Trucy find out they're related yet?

at the end Phoenix and Thalassa talk with each other and they think it's almost time to tell them.

I get the feeling this is gonna be really disappointing. I mean they've spent the past two games teaching you not to care about Trucy in any capacity and this implies that she's a main character when she isn't.

So, every AA game except for the first two have the killer involved later in the plot. Does guitar Jesus have any mention or connection to the later stories?