also if you could clarify how data I input and tweak is reused.
Your terms are a bit scary (basically if I write a book, you can 'publicly perform it and distribute it'?)
per:
By making any User Content available through our Services you hereby grant to Sassbook AI a limited, non-exclusive, worldwide, royalty-free, transferable license to access, view, use, copy, modify, publicly display, publicly perform and distribute your User Content to the extent reasonably needed to operate and provide the Services to you.