It also differentiates her a little from the "usual" japanese high-pitched full of energy voice acting and makes her a little more mature / calm.
While I get that Japanese voice acting can be often like you claim, I really wouldn't call Toyoguchi's voice acting high pitched or high energy. I'm assuming that you've heard it, of course. The biggest issue that I have with the BBS dialogue is often not the caliber of the voice but that it seems the English actors don't quite emote as much at times.
Hearing someone talk a foreign language and simultaneously reading a translation of what that person just said feels kinda off to me
I totally get that, but part of the problem with dubs vs subs is that unless you are proficient in Japanese it is always going to involve translation somehow and your understanding of the situation/characters is still going to be fully dependent on said translation/script. Whatever voice is coming out of the characters doesn't make a huge difference to that.
So the problem still always comes back to how good is the localization and does it actually accurately capture the same intended feeling of the original language.
Personally I generally really like the localization up to KH2, Coded is fine, BBS is mostly fine and 3D is okay enough, though has more problems for me personally (though I will admit they tried SO SO hard on those dreameater names I gotta give them some credit for that, despite the puns working so much better in Japanese). However a lot of that is literally just the script itself, and while the script is better in Japanese, it's still...not that great.
KH3 had a few issues with the localization at more crucial points (which I know caused some confusion), but was generally fine and at times I think made a few very good decisions about when to NOT directly translate.
For example, one huge difference is in the scene after Kairi and Sora are escaping the dark together right before the first time reset in the graveyard. In Japanese Sora straight up tells Kairi she's "strong", whereas the translation opted for him saying she "made him feel strong". I think this was a good decision considering the cultural difference that people have over the definition of "strength" that I still see people repeating even now about how "weak and useless" Kairi is even though she literally saves Sora's life but hey. I think because in the west there seems to be much more of a reluctance to accept strength that isn't bashing stuff in the face. (or so it seems to me, sorry if that offends anyone). While I would have preferred if Sora was able to have the focus be on Kairi as it is in Japanese, I completely understand why they went that direction. It helps western audiences appreciate the sentiment rather than immediately raging out like BUT SHE ISN'T STRANGTH!!?!??
Funnily enough I've always sort of wanted to make a bunch of videos that breaks down the localization for all the games in chronological order and talk about what works and what doesn't but I had no idea if that sort of thing would actually be popular enough to bother with.
Overall I think the localization are generally pretty good most of the time, but I still personally believe (J)Sora is always going to be my favorite Sora because he's just that much more...naturally upbeat sounding? I dunno. Like, not trying to bash HJO or anything, and maybe some people prefer this as adding to depth of character but sometimes HJO sounds like he is only "trying" to be happy (while struggling with something else) whereas Miyu often just sounds...happy.
And a special place in my heart will always remain for the Spanish dub of KH2. Never fails to make me laugh at how the length of what they want to say vs the time they have to say it often does not match up and the amazing way they roll their R's when shouting Rrrrrrrrriku!!