Rule of thumb, Gabriel:
anytime the original/Roman* Latin you read seems wrong, it's 95-99% probable the error is not in the text but, in fact, in your mind.
Now, a really proficient Latinist, who has read with fluency many works, may spot some 'lacuna' or a place that both doesn't make sense AND is happens to be disputed across critical editions of the text in question. But, as a relative novice (albeit reading Livy), always believe that ultimately, the reader is always wrong, not the text
Consider the text you read as "sacred" as it being practically impossible that you could
of your own volition either add or remove a word to make it better.
It is true that once a upon a time (in a very different age), Latin words would be written together, almost no if any spaces used in the text, neither any kind of interpunction, so the sentences or paragraphs looked like a giant infinite word: and there one had to wonder where a new clause begins etc, but you can trust me that is almost never the case with texts you come in contact today.
*often times, the same rule will apply though even with medieval or later Latin, if done by some reputable authors, at least; they are often indeed smarter than you/the reader ;P