No. Colorado has no law which forbids a sex offender from being a landlord or requires a landlord to inform them of being a sex offender. Your friend was free to check the Colorado Sex Offender Registry prior to signing her lease.

Colorado also has no law which would require a roommate to divulge that they've been accused of or convicted of child abuse/neglect. This would also fall under your friend needing to do their due diligence and checking the background of their roommate prior to signing the lease.

If their roommate is currently on any sort of court supervision which prohibits them from living with or being around children under the age of 18, then that would be an issue they have to deal with and would have no bearing on the validity of the lease.

The domestic violence law does not apply to your friend, unless your friend's roommate has committed domestic violence against your friend or child and your friend has reported that to the police and followed the proper procedure to move out under the law.

If her roommate has not committed any domestic violence against her or her child, then the domestic violence law does not apply to her.