Hello! Thank you so much for your kind comments!
The credits page could not be finished on time so it's true that it's empty.
The music/sfx bug is known! And we'll fix it soon~ Though it'd obviously not count for the jam entry but we want to have at least a playable demo uploaded as well!
The siblings are a Brother (Tau) and a Sister (Jannali)! But there must be a typo so thank you for noticing!!
There is some kind of bug that wouldn't let you play the actual game, as the tutorial is actually not finished and so you are kind of stuck in there :( Sadly we were not able to fix that on time for the jam but we'll definitely fix these things to have a working game~
i hope this answered all your questions and thank you again for the feedback! 💕