I'm curious as to how correct translations are decided. In English, it feels much more natural (to me, at least) to say "How does one search through the text?", assuming we're talking about, perhaps, trying to find keywords on a webpage or in a text document. Certainly "through" is not a valid translation of "i", but usually one translates more the meaning of the sentence and not just every word literally.
In general, we accept as many correct variations as possible, as long as they don't deviate too far from the source sentence. But trying to find a perfect default translation can be a huge hassle.
The main reason for not having the most idiomatic translation as the default is often the reverse sentence. What we enter as the default also turns up as a "translate into Swedish" exercise. You'll frequently find that these are a little too literal in English, as compared to the more idiomatic translation. This is on purpose, since the goal is to teach Swedish words and sentence constructions. If it gets too ridiculous, we'll turn the reverse sentence exercise off, but if we did that too often, there would be too few of those left.
So it's a tradeoff between, really, teaching good Swedish and having/teaching good English. Sometimes we're in the wrong, and often there's no perfect answer.
Having said that, there's a slight (but usually irrelevant) difference between searching a text and searching through a text, and Swedish can use söka igenom texten for the latter. :)