Certainly one translation doesn’t have to line up with all the others. If they all do, then you might wonder if they are all following a translation tradition or copying from one another. So, I wouldn’t fault the NRSV for being different. However, I think it is bad for a different reason. θλιψις means pressure or constriction, and I think it is probably an onomatopoeia (sounds like what it means — say “thlipsis” a few times). So, that’s why a word like “tribulation” is better. I think “constriction” and try to come up with an English word that applies to people or a group of people, as “The Great Constriction” isn’t something we would say in English. But the word “ordeal” doesn’t do it justice. If I had to back-translate “ordeal,” maybe I would use πειρα or πειρασμος, or something like that, such as in 1 Pet 4:12 (πυρωσει προς πειρασμον), or Mark 14:38. If I said that cleaning up my messy house was a big ordeal, that would not imply any sort of external pressure, or that I was subjected to “great tribulation.” ¶ It is also not fair for you to translate by exegesis. The word tribulation may be the best word but the end doesn’t justify the means. You can’t say that it is so because this and another verse obviously refer to the same thing even if they don’t use the same word, and so on and so forth, and this thing and that, and the “two witnesses” of Revelation are the church, and that we know that various things are yet to happen, etc., etc. This is begging the question, circular reasoning, assuming the conclusion in the premise: “There will be a ‘Great Tribulation’ to come and that’s why it should be translated ‘Great Tribulation.'” Even if I agree with you that there will be such a time of “great tribulation” to come in the end times, I can’t agree with that line of reasoning to justify the translation.