Salam Euphoric.
I would not call these "variations," rather they are "errors".
In the process of copying the Qur'an and spreading its message, it is clear that scribal errors have taken place where a word or words have been mispelt or even omitted (I think there was a verse 57:24 where "Huwa" was missing from some versions).
The solution is a little bit laborous but simple. All scribal errors are to be reviewed, with the context being the prime determiner of which was is correct.
In the absence of context, then we need to look at other verses that support or reject the scribal difference (is God "King" of Judgement Day or "Possessor" of Judgement Day?).
Take for example 30:2-3, all "codified" versions have Rome losing then winning. Yet, the context screams the opposite. Digging a bit deeper, we find that there were some versions of the Qur'an that did indeed have Rome "winning and then losing" - as I said, it is quite a task.