Pre-draft Björnfot was ranked 7th best euro prospect, Heinola 4th. So it's not like they we not ranked high. Scouts sometimes see more NA games and like the NA players better. We are lucky the Kings euro scouts have been good recently but Byram should of went as the first D off the board, let's not get crazy here.
They were both underrated pretty much the entire year, but that's often the case with euro prospects who don't put on a show in international tournaments. Like you saw with Broberg and Podkolzin were both able to maintain their hype from the Hlinka and onwards and was always talked about completely differently than Björnfot and Heinola.
But yeah, both independent scouting services as well as a good deal of NHL teams seem understaffed when it comes to european scouting. I could be wrong but I think there are some teams which only have one scout in all of Sweden and Finland and that's just nowhere near enough to be able to get complete or even close to complete coverage of the prospects in those areas.
And then don't get me even started on the NA-based media guys who put out lists, they have very little credibility when it comes to assessing european talent yet feel comfortable making sweeping declarations about draft classes' and its prospects and especially hyping NA talent up when there may be equally great talent on the other side of the Atlantic Ocean but they just don't pay attention. Or they end up overhyping certain european prospects just based off a five-game tournament and keeping them high on their lists even if they haven't performed all that well in league play.