I do not tolerate this sort of drug use in my house but before I go and bring in law enforcement is there anything I should do?

If your lease does not have restrictions on occupants, talk to code enforcement and see if there is anything you can do.  

The term “real estate brokerage activity” has the same meaning as in the federal Secure and Fair Enforcement for Mortgage Licensing Act of 2008.(2) The following persons are exempt from regulation under part III of this chapter: (a) A person acting in a fiduciary capacity conferred by the authority of a court.

But not enforceable.

In 2016 legislation was passed in the City of Dallas mandating certifications of owners of building condition and random inspections on most rental property.

He states he has this paperwork and has been to the city about this because code enforcement was hassling him and city confirmed he did not need permits for the units.

I personally never had to use that language and a magistrate judge may decline to enforce (rightfully or not). 

I think differences come into play when it's a mobile home, which require different types of code enforcing and may rent a little less.

I don't agree with many parts of this proposed legislation.

It won't scare them away, but would maybe capture a pic of them to give to law enforcement who may be able to charge them with trespassing and/or breaking into a dwelling.