The main thing here is that all subtitles from Undertexter.se (the raided site) are entirely fan-made, e.g. dialogs interpreted by the sites users, and then translated according to their own interpretation. I actually don't understand -how- this could be copyright infringement, so if anyone could explain it for me, I'd be glad!

It has been explained in several of the comments. It constitutes the creation of a derivative work.

Before coming to Sweden I would have probably agreed with that, now, however, I am inclined to believe Swedish laws are only applicable to Swedish people where and when America is not involved.

Other than all those times, yeah, sure.

It seems like this might be the most important comment here. If so, then the law is being discarded just because the companies at hand are pushing their weight around.