Legally, does it matter if POTUS doesn't know what s/he's signing?

Executive Orders get modified all the time. Usually only once per administration, but minor errors are corrected or the order significantly changed.

Another question is could the President backtrack, and say “I didn’t really know what I was signing then”.

Or maybe the President does not believe he actually signed something into law, something that was already signed and assumed to be law several months ago.

I am assuming that in the House and Senate, the speaker of the House and the Presiding officer of the Senate are essentially the ones who decide what laws their respective houses approved into law, and if the actual elected representatives are not happy they could just vote them out, in an informal process.

Suppose the President was assumed to have signed something and then right afterwards he fell into a coma. Some people question whether he actually signed it.

Or could the President backtrack and say he didn’t actually understand the full implications of what he was signing, and maybe know he wants to retract his approval for the law. Seems like it could be a Constitutional grey zone.

I’m not familiar with this particular law, so they possibly did amend it to remove any possible poor construction of it.

Had this law survived, any judge who looked at this law and voided all marriages in the State of Texas would have been carted out in a straightjacket, impeached, and then the new judge would have restored marriages.

Was this some sort of jab at proponents of traditional marriage at the time, or did anyone really believe that the State of Texas would be left marriage-less?

How do you imagine bills appear? By magic?

There are people who not only read every word of a bill but actually wrote the words. They know what it is they wrote.