Not only Texas, but Georgia and Louisiana had relevant cases.
WHITE v. CANNON, 73 U.S. 443 (1867) (re State of Louisiana)
The ordinance of secession passed by the State of Louisiana, on the 26th of January, 1861, was a nullity, and did not affect the previous jurisdiction of the Supreme Court of that State, or its relation to the appellate power of the Supreme Court of the United States.The objection that the judgment of the Supreme Court of Louisiana is to be treated as void, because rendered some days after the passage of the ordinance of secession of that State, is not tenable. That ordinance was an absolute nullity, and of itself alone, neither affected the jurisdiction of that court or its relation to the appellate power of this court.
WHITE v. HART, 80 U.S. 646 (1871) (re State of Georgia)
At no time during the rebellion were the rebellious States out of the pale of the Union. Their constitutional duties and obligations remained unaffected by the rebellion. They could not then pass a law impairing the obligation of a contract more than before the rebellion, or now, since.
Darn. It looks like someone named White was barnstorming and making a living out of losing secession cases.
It looks like according to the legal cases you cited that the states were still part of the Union, thus, the actions committed by them against the United States were treason.
You aren't suggesting the U.S. Government is in the habit of soliciting patsies?
I happen to know that they had two very upstanding patsies in U.S. vs. Miller. One obligingly died, and the other went broke, so his attorney didn't even show up for oral arguments. His brief sat silently at the appellee's table.
The U.S. Government gives nothing but a fair show all around.