Since men are flawed translations will have flaws. To combat this committees do translations to reduce errors. The problem exists of time. Language changes over time. Therefore a good translation in 1611 becomes flawed with this change of the language. Therefore current translations need to be used. There are parallel translation Bibles that have 4 translations side by side.
OK, let's take the word "then" that you used the word "simultaneously" in 1st Thessalonians chapter 4 verse 17. What is it about this word that you guys think you need to retranslate this? Seriously!
Definition of then:
1- at that time; at the time in question
2- after that; next; afterward
3- in that case; therefore
Definition of simultaneously:
1- at the same time
2- at once
3- concurrently
Now I used Bing to look these two words up. Usually if two words have the same meaning you will find them in each others definitions. Not the case here.
Then can have a meaning that is close to this but it has others and to just replace it to make a point or to make a theory more plausible is inexcusable.
This is the danger of rewriting the Bible at this time. You have to KNOW the earliest version to catch a later version that is tampering with the TRUTH.