In the Netherlands we are also taught a swan could break your arm if you get too close. I don't know if it's true or not because I've been too scared to find out.
They've got a pretty savage and scary charge to them, it's highly likely they've startled more than one person in a park who've turned to run, tripped and fallen across steps or rockery edges and come out badly injured.
https://outdoorswimmer.com/coach/myth-busting-can-a-swan-bre...
The beak is probably more dangerous, or at least give you a nasty pinch or nibbing.
As I said, and supported by your link, I can't see a swan directly breaking a human bone - but they sure as hell can knock one arse over by charging and causing a step back fall over. That'll do some damge in some cases, easy.
If we play conkers with each other's bones the swan will lose.