Hate Crime section
This article discusses the track record of hate crime legislation.
If you define success as hate crime laws actually deterring hate crimes, then they probably aren’t successful by that standard — since no good research shows they’re an effective deterrent. But if you define success as hate crime laws providing resources for marginalized communities so they can feel protected and accepted, then there’s a strong argument, experts said, that they’re successful.
If the discussion is whether hate crime legislation has reduced hate crime incidence, there is a confounding factor, which is that the majority of hate crimes go unreported. The first link corroborates the shortcoming of official statistics.
Over the past two decades, the FBI reported between 6,000 and 10,000 hate crimes each year in the US. But when the US Bureau of Justice Statistics surveyed large segments of the population between 2007 and 2011 to try to gauge the real number of hate crimes, it concluded that there are nearly 260,000 such crimes annually.
However, without hate crime legislation, there would be no effort to categorize or track hate crimes, or have any information about their frequency. So, without the legislation, you don't even have a framework to begin studying and addressing the problem.
Terrorism Law section
In America, it is also difficult to measure the effectiveness of terrorism modifiers to criminal law. The reason for this is because Title VIII of the Patriot Act modified terrorism criminal law at the same time that other provisions* of the Patriot Act provided for numerous other measures to prevent terrorism. Therefore, it is difficult to separate the success or failure of individual provisions that were instituted simultaneously, except by correlating terrorism frequency with the expiration dates of individual provisions (there have been various extension bills to the Patriot Act, causing some provisions to expire as early as 2006 and others as late as 2019). The sample size of terrorism in the US may also be too low to make such a correlation with any statistical significance. Ultimately, I would conjecture that the Title VIII terrorism laws likely have not been an effective deterrent at all, because not enough people know that Title VIII exists, nor the severity of the penalties it establishes.
*Provisions originally created by the Patriot Act include various expansions in funding for counter-terrorism centers and task forces, enhanced surveillance procedures, anti-money laundering measures, border security, removing investigative obstacles, a fund for helping victims, increased information sharing between agencies, required prioritization and dissemination of collected intelligence, and miscellaneous provisions for hazmat suits, electronic surveillance, first responders, studying biometric identifiers, study of a no-fly list, private contractor security, and regulation of charitable telemarketing.