There definitely can be retaliation. The "anonymous" surveys on a company site have an IP address. Some network guru can just trace it and figure out who you are. There are also keyboard trackers. Your best bet is to do it from a public library or an old school internet cafe and use a throwaway account. The nature of the complaint can also reveal who you are.
About ten years ago, there was a sorority video in the south that went viral. They were accused of racism. I am Native American and saw the video. To me, it was not racist at all. It was just a school spirit video IMO. I joked with a white southern coworker about that - a recent college graduate familiar with that particular university. We sarcastically said to each other "Oh yeah, they're racist" as a joke since we both thought the video wasn't racist.
But a manager (let's call him manager A) overheard us and thought I was not joking. He thought I was serious and blatantly accusing that sorority of racism. So, he angrily confronted me and asked if I ever used the n-word. Then he went off on a long diatribe about why southerners are unfairly accused of racism in such a way that he clearly thought he was morally superior while being convinced I had wrongfully accused that sorority of racism (which I did not). So, I reported that whole diatribe to HR.
It turned out what happened was HR did an investigation and reprimanded him. But my direct manager retaliated with genuine racism. I later saw the details of his performance review of me. He had gone off on a deep tangent labeling me as a coward who doesn't stand up for himself. It was really extreme to another level - the type of racism seen in 1950s Cowboy-and-Indian movies where Native Americans were depicted as cowards who always lose to white supremacists.
That was ironic. Manager A confronts me about accusing a southern sorority of racism when I did not. Then I reported that to HR which reprimands Manager A. But Manager B, my manager, retaliates with blatant racism - the type of attitude seen in Old West films of the 1950s. Go figure.
I responded to that and called out the racism. I reminded HR that I had Native American relatives who were US Marines - one who was on the front lines at Iwo Jima. I thought the "coward" accusation was blatant racism.
So, in hindsight, it was best just to leave rather than report that initial incident to HR. I stay away from HR these days. As for Manager B, he got fired about a year after I left. I guess his racism ran its course. Maybe he should try to assert his "invincible" bravery by beating Jon Jones in an MMA fight or one-on-one blocking drills with black or Samoan linemen from the SEC or Big 10. It would be fun to see the outcome - flying through the air backward.