Involuntary manslaughter would probably not stick as a charge

https://zealousadvocate.com/resources/law/involuntary-manslaughter-texas-legal-insights-and-real-world-perspectives/

Involuntary manslaughter refers to the unintentional killing of another person, usually through reckless behavior or negligence. It’s different from other homicide offenses because it doesn’t require intent, deliberation, or premeditation.

The following factors influence criminal liability:

• Actus reus (guilty action or conduct): evidence that the accused committed an unlawful act that directly led to a person’s death or acted in a way that demonstrated criminal negligence or recklessness.

• Mens rea (intention or knowledge): while intent to kill is not required for Involuntary Manslaughter, there must be evidence of negligence or recklessness. For this, the accused should have been aware, or at least reasonably should have been aware, of the risk or danger their action (or inaction) would create.

• Causation: There must be no doubt that the accused’s reckless or negligent behavior led to the victim’s death. In other words, the victim’s death would not have occurred without the reckless or negligent behavior of the accused.

It's the actus reus part that I don't think checks out with this charge. They weren't acting unlawfully. They weren't acting criminally. They were doing their jobs within the law.

https://www.dwilawyerstexas.com/tx-penal-code-15-02-criminal-conspiracy/

Texas law prohibits criminal conspiracy, which is the agreement to commit a crime. If two or more people devise a plan to commit a felony, and at least one of them acts in furtherance of the plan, each person may be convicted of conspiracy to commit the object of the conspiracy.

Again, they weren't acting unlawfully.

It's actually legal for legislatures to pass legislation that kills us "passively." Otherwise, if it wasn't legal, homeless people could sue for their conditions and win. People who die from lack of medical care could sue and win. People who die in car accidents could sue because we dont have public transportation due to oil industry. We could sue due to climate change effects and government policies that worsened that. They currently cannot sue lawmakers and win those cases.

I am 100% for having laws in place that charge lawmakers with crimes for policies like this. But they currently don't exist how we want them to.