The story with the Spanish translated. The AO3 version of this story has translations provided as mouse-over text on the relevant lines, so you too can learn Spanish with Luz!
["Who does that little shit think she is?!"]
["No, mom, she didn't mean it!"]
Amity sat at the steps of the Noceda family's front porch, hunched over, knees folded, quietly combusting from shame and wishing she could make the earth open up beneath her feet and swallow her whole. Just her luck, she figured, that Luz had asked her not to do magic out in the open. How did humans get anything done if they only cast magic in secret?
["Oh sweet Mary full of grace... I tell you girl, had I been a different sort of person...!"]
["It was me, mom! I'm the one that taught her to say that!"]
Amity slapped her forehead; here she was, intruding on her friend's life because—ever the selfish, lovesick fool—she just had to blunder into inviting herself over to Luz's world after the human said she'd been expected to return at a specific date.
["But, I don't get it... How could you tell that little white girl to disrespect your mother like that?"]
["Mom, mom; it's not that, it's just... I didn't tell her what it meant..."]
Amity hugged her knees closer to her body and sighed deeply; this was her last Grudgby match all over again. She should've warned Luz that she was going to try to impress Camilia by using one of the words Luz had taught her. The word came from a language spoken in the far-off lands of the Republic of the Nocedas, and Amity just had to show off how well she listened to what Luz was teaching her.
Instead, Amity had mangled the pronunciation and very likely sparked an international disaster between both worlds. At least she couldn't hear any more shouting from behind the front door; Luz, ever the loyal friend, had probably saved her from… Well, she didn't quite know how things were settled in the human world, but considering Luz's go-to solution for everything was duels to the death, Amity could hazard a guess.
Amity turned her head as she heard the front door's handle turn. Her eyes widened when Luz's head peeked out of the half-way opened door; "Luz! I really mess—"
"—A-ha-ha-haaamity!" Luz grinned widely; "¡Amiga! Buddy! Gal pal!"
"Uh…?"
"You know I love you, right? And you love me too, right?"
Amity swore she heard her ribs crack as her heart pounded violently against her chest; this girl was going to kill her! How could she say things like that so easily? Amity could barely keep her sentences coherent half of the time! "Buh…" she replied, feeling the heat on her face reach her ears and neck. Oof, she was getting light-headed again.
Luz stepped out fully into view, clasping her hands together and toeing the floor with her right foot in a display of adorableness that would be forever seared in Amity's mind. "Yup! Bestest of friends, so much love between us!"
A hand shot out and gripped the top of Luz's head. "Luz Noceda, you apologize to the poor girl right this instant! She looks about ready to pass out," Camilia said, turning her daughter's head to face her. Luz giggled nervously under her mother's unamused gaze.
"A-apologize?" Amity wondered if she was even tall enough to ride the roller-ghoster of emotions that was spending more than five minutes around Luz; she was going to get whiplash from the constant love highs and friend lows! With a sigh, she stood up and turned to face them both; no sense in compounding her diplomatic bumbling with impoliteness on top of it all.
Luz, meanwhile, had turned a lovely shade of red which Amity recognized as the adorable color of her embarrassment (not that she kept track of Luz's different blushes or anything). "So uh, funny story! You know that really long list of words and phrases I taught you a few weeks ago? Maybe don't, um, use them."
Amity nodded solemnly; she had really screwed up, hadn't she? "I suppose it's for the best; I'm sorry, Mrs. Noceda, I was trying to impress you—er, that is, make a good first impression—but I messed it all up. Please don't blame Luz; she tried really hard to help me learn your language, I just didn't listen well enough to her lessons."
Silence, broken only by the hum of a lone car passing by.
"...Mija, is this the girl you texted me about?"
Luz's blush intensified. ["Yes, mom, and she doesn't actually know about that, so—"]
["—She is way too nice of a girl for a little troublemaker like you."] Camilia turned to Amity with a smile. "You have nothing to apologize for, dear. In fact, it's Luz who hasn't finished apologizing to you; have you, Mija?" she asked, gripping Luz's head tighter.
"Eep!" Luz eep'd, bringing her eyes to meet Amity's; she sighed, letting her shoulders sag. "Fine… Amity, all those words I taught you were curse words. Pendeja means—"
Amity's eyebrows shot to the sky as her heartbeat raced for a different reason now. "—I placed a curse on your mother?!"
"Nnnnot exactly," Luz began, shrinking a bit into herself, "More like, you called her a... dumbass?"
Silence, broken only by the sound of a passing cyclist's bicycle tires.
Amity's blush somehow worsened as she slapped both hands on her face. Peeking between her fingers, she turned to Luz's mom first. "Oh my gosh! I am so sorry, Mrs. Noceda, I swear I didn't know!" Immediately, she turned to the younger Noceda and brought her hands out in front of herself and towards Luz, fingers wriggling in vaguely neck-chokey motions. "And you—!" she began, her eyes flitting wildly between mother and daughter. Mrs. Noceda was from a healing coven, right? If she killed Luz right now she'd be fine, right?
Camilia smiled, easily deciphering the look in Amity's eyes. "Oh, don't hold back on account of me," she said, releasing her daughter to her fate, "Better get your flirting in while you can because Luz is going to be grounded for a good long while!"