To be honest, that was a bit hard to read.

Seems like the concerns were:

• Confusion on UA's part on Cuban Visas
• Lack of research on which terminal UA left from in HAV
• Dirty plane
• Inability to pass through TSA for a flight the next day

While I don't disagree that your experience was poor, especially in first class, really the only things that were within UA's control was the info on Cuban visas at SFO and the dirty plane, which may have been due to needing to get the flight out on time, I don't really know. But UA doesn't clean the plane themselves either...so something might have happened with the contracted crew.

It technically is correct to not allow you into the secure area for a flight the next day.

If you do write it in and complain, consider condensing the main facts that were outside of your control and you may get a gesture thrown your way