[Originally went through it for a friend and my own curiosity, but figured I might as well share it. Mostly minor stuff, but gives more insight in the feeling behind the scene, as well as some nuance. I really like the localization but some parts are just nice to know. Have fun!]

Note: I'm not trying to make this sound natural or pretty, just as plain as possible to convey the feeling.
English in quotation, Japanese behind the >.

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"why so sad"
>"what's with that face"
(which is funny bc it can mean 1) why so sad but also 2) your face doesn't have marks anymore)

"you let them reduce you to this?"
>more plainly, "I can't believe you let them control you like that"

"I thought you outgrew the marks under your eyes"
"Are you sure you have no more need for your protective/lucky charms"

"So?"
>"Yeah"

"you look like you need them"
> "Then don't give me a face like that"

"Stop it. the whole act"
> "No, you. Stop pushing yourself"

"I thought it was all for her"
> "You never once stopped looking for her, right?"

"At first"
> "I wonder"

"I sacrificed everything to try and track her down"
> "I even went as far as siding with them , giving everything in my search"

"you're the one who went off and made other friends. Left me and her both in the dust."
> "You seem to have forgotten all about it, making different [new] friends and went off having so much fun"

"it infuriated me how you just exited our lives"
>"I couldn't feel anything else anymore except for how infuriated I was with the way you were being"

"i lost all sense of purpose"
>"I got the feeling we/I had strayed from our objective"

"I didn't forget you"
>"There's no way I'd forget"
(Japanese here is much stronger)

"Yes..I know. You wouldn't do that."
>"Yeah, I know. You're not the type."

"but, I was jealous"
>"It's probably.. because i was envious"

"you admit it"
>"How earnest"

"Well.. If i make it back, you won't get it out of me a second time."
>"Something embarrassing like that, if i return a human i won't be saying it again"

___

pre-battle:
"stop it, isa"
>"open your eyes, isa" or "wake up, isa"

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I don't think i'll be going through the entire clock tower conversation since it's lengthy, but know that Saix/Isa called Lea/Axel a "crybaby" canonically :^), and the marks under his eyes were referred to as (protective/luck) charms of inverted tears, which means it functions much like a bit of magic to kids. Apparently this is something Isa had taught Lea......because Lea was a crybaby.