I'd take the main lesson to be once you know you have a cockerel, leave him be. There are roosters out there that can be pet and loved on from birth who stay friendly, but there is a much larger trend of cockerels with a lot of handling who process our version affection and contact very differently indeed. A good rooster takes care of his hens first and foremost, but a very close second is he must be pleasant to be around, especially in a flock like yours.
Cockerels who get lots of handling lose the personal space bubble that serves everyone well as they get older. Fear is the wrong word- respect is the right word. None of my 10+ roosters/cockerels are afraid of me. They respect my space and I respect theirs. They move out of my path (with zero urging), if I need to catch a hen inside or outside the coop, they do not interfere.
From the time I know they're boys, I don't pick them up unless absolutely necessary, and then only in the coop at night unless it's a medical emergency. My hands do not mean food to them- they are never hand fed (neither are the girls). Actually my hands mean nothing at all as far as they're concerned. I have no worries about which rooster is where and what he might do. Should that become a problem, I have zero qualms with elimination- keeping chickens is supposed to be enjoyable!
In the same way that your one cockerel felt just fine about jumping onto the back of your Bielefelder roo, their loss of respect for your personal space makes you a prime and easy target... after all they've been welcomed! If you watch your chickens and evaluate the pecking order, it's much about who gets the right-of-way, who gets first access to the food, and who is allowed to peck who without consequence.
I have a job to do - I bring food and water and clean and collect the eggs, and tend to anyone who is sick or injured. And of course to visit and enjoy everyone!! The cockerels and roosters have a job. They look after the hens, break up squabbles, mate the hens, and act as an alarm system for predators.
Not every roo is a good roo, regardless of how they are raised. I have sent some 'packing' who treated the hens badly. If they turn into terrors for the hens as soon as the hormones hit, they are eliminated. Nobody gets to make my hens run for their lives. There have only been a couple who posed a problem to me as a person - out of dozens and dozens- and they were also sent 'packing' as they had zero excuse to act that way. One was that way from the time he was a bitty chick. The majority of my cockerels have been rehomed, and I keep the ones I want.
If you're going to expand your flock, recognizing the cockerels early and taking a hands off approach might be helpful to the end result.