The language spoken by the high command on High Charity is Sangheili.
John reports to Dr. Halsey "Returning from Twenty-Three Librae, Planet Madrigal." 23 Librae or 23 Lib is a star in Libra constellation. It is located about 83.7 light-years from our Sun. With an apparent visual magnitude of 6.45, it is not visible to unaided human eye. It has two planets, one of which could have been named Planet Madrigal for the series.
Reach is said to be located in Epsilon Eridani, that is a star, common name Ran, in the constellation of Eridanus. It is at a distance of 10.5 light-years from our Sun. it has an apparent magnitude of 3.73, making it the third-closest individual star or star system visible to the unaided eye.
Article 72 seems to be some clause that allows the UNSC (United Nations Space Command) to execute any threat to the safety of humankind. Here, Kwan Ha doesn't seem to be any threat to humankind by farthest stretch of the term, so this clause is being used in an unethical manner, just to silence dissenting voice.
The title sequence doesn't appear until almost 18 minutes into the 59 minutes episode.