Learn Spanish (Latin America): Es terrible que el requisito no sea claro. - It is terrible that the requirement is not clear.

The phrase es terrible que expresses a strong opinion or emotion. In Spanish, when you use a phrase like "It is [adjective] that..." to judge or react to a situation, it triggers the subjunctive in the second part of the sentence.

Where does the word sea come from?

Sea is the present subjunctive form of ser (to be) for yo, él, ella, and usted. Ser is highly irregular in the subjunctive, so it doesn't follow the normal vowel-swapping rules. Here, we use it because we are talking about el requisito (an "it").

Why do we use ser (sea) here instead of estar (esté) with the word claro?

We use ser because being "clear" (or unclear) is an inherent characteristic of this requirement. If a rule is poorly written, that lack of clarity is a permanent feature of the text, rather than a temporary state.

Is requisito a false friend for the English word "requisite"?

Not exactly a false friend, but it is used much more often! While in English we usually say "requirement," Spanish uses requisito for all kinds of everyday requirements, like the paperwork needed for a visa or the skills required for a job.