My rabbit is neutered and he grunts often: when he hears food being dispensed, when he’s annoyed, when he wants attention, when he’s impatient for treats. Grunts don’t always mean aggression or anger, but I agree with Bam about bunnies having different expectations and desexing the rabbits.
I’m learning that bunnies can be pals one minute, and jealous and vengeful the next. You just have to figure out the triggers (even seemingly insignificant things), and create distractions or make adjustments, whether it means medical, or changing cage set-up, etc. Just keep trying different things.
It’s good that you’re so observant and that you’re researching a lot, because you learn so much from other people’s experiences. I had to change my expectations a bit. The most important thing I learnt is that not all bunnies will have a snuggly relationship but as long as they don’t fight, it’s a good thing.
Also, grooming each rabbit individually in a comfortable space has helped me bond and build trust with my kid’s, reducing stress. When Thor gets annoyed with Crysta, she will sometimes run to be next to me, and this started after I groomed her on a towel on the washing machine. Thor hates being picked up, so I groom him on the floor most of the time. Little adjustments like that will make your life so much easier than trying to do things the way you see people do it on YouTube, etc.
Good luck with Cadbury and Bonnie.