Hi! Thank you so much for playing and for your kind words!
As for the Spanish translation, I'd love to add it, but I'm a solo dev with no Spanish speakers on my team. If any fan translators want to help, I'd be happy to collaborate!
Now, let's get you those missing endings for Xiao! Here are the hints:
Ending 6: When you are at his laptop, choose to find something else to do, and then choose to "Just wait" for him at home.
Ending 8: Choose to "Take a nap". Then, let Aether walk you home. After the... incident, choose not to forgive Xiao.
Ending 11: This one is a secret!
First, make sure you have already unlocked Xiao's Ending 10 (Love Till the Grave). Then, read Lumine's messages on the laptop and agree to travel with her. During Lumine's route, when things get creepy in the hotel room, choose to grab the keycard and run away!
Hope this helps! Good luck! 〜(￣▽￣〜)