Bible changed? Example from Arminianism vs Calvinism

From my understanding and through examples in history and my life as well, God allows good and bad things to happen. Although I would always be curious as to why certain things happen, especially when it comes to bad stuff, I know His reasonings would go beyond my comprehension and understanding as He knows all. God will only allow certain things to happen if He wants it to happen. The devil, on the other hand, can only do things as he is allowed to by God. With that being said, would it be possible for God to allow the devil to skew His Word (Bible) in any way, shape, or form? Knowing that the devil is pure evil and one who deceives, manipulates, and twists the things of God, one would wonder what kind of things he would do prevent Christians from fully benefitting from reading God's Word and progressing in their spiritual life. An example that I think could be something that he would do or has done is change certain words in the Bible. As you may be aware, one word or phrase can have the power to change a sentence or meaning completely, whether in the Bible or just everyday conversation. **John 3:16** > For this is how God loved the world: He gave his one and only Son, so that everyone who believes in him will not perish but have eternal life. > ~ NLT (New Living Translation) > For God so loved the world that He gave the only begotten Son, so that everyone believing in Him should not perish, but should have eternal life. > ~ BLB (Berean Literal Bible) Both are the same verse, that pretty much says the same thing, but one glaring difference is the words **will not** and **should not**. Would it be fair to say that **will not** is pretty definitive, that if I truly believe in Jesus, I **will** be saved regardless of what happens afterwards? As opposed to **should not** or **shall not** (in other translations), which would indicate that it could happen but not guaranteed. For this verse, I would think that figuring out which translation or meaning is the true meaning would be pretty crucial. One implies that I'm good once I'm saved and the other implies that I should be good to go once I'm saved but... It would seem that either you can or cannot lose your salvation once you accept Christ. If you **can't**, then that would allow me to focus on other aspects of the Bible and if you **can**, then that makes me wonder what I must do to make sure that I keep it that way and not mess up (unforgivable sin comes to mind). God is not one to cause confusion when it comes to those that want to seek Him and His Word, so I'm wondering to what lengths or permissions would He allow the devil to do his thing? These are beliefs from **Arminianism** vs **Calvinism**, which if I'm not mistaken, for this topic, is that you are good once you're saved vs you can be unsaved, respectively. I'm not asking which view is correct, but clarification of which words would more accurately reflect the original texts/Scriptures. Would it be **will** or **should**? And if you read my responses in the comments, I made a point about why I'm not convinced that they are the same words. Unless I'm misunderstanding something and that back in the day, those words meant the same thing or something, those two words do not convey the same meaning to me. I would be much more convinced that something was or wasn't going to happen with the words **will/will not** than **should/should not**.