It can take time, yes, even years. I recall when I first encountered the legal system it didn't know which of us was the problem, or even in both of us. In municipal court she faced a charge of Threat of DV. She refused to plea deal and after a few months of continuances were had an end-of-day trial, she admitted that the recording was her making threats but "that's how we argue". Um, her, not me. Anyway judge compared it to a drunk man coming home saying "if I had a gun I'd kill you". He cited case law (decisions, not written law) where a threat was not enough, it had to be an "imminent" threat. So he found her not guilty despite emphatic threats against my life and case dismissed. A couple years later she had the case expunged, so now it's as though it never happened.
I figured that if it were me who had made threats it wouldn't have turned out so well. But as a woman and a first time offender, that's how it ended for her. I was bummed that he didn't remind her she better not do it again. I walked out feeling that she now had precedent to make whatever threats she wished against me as long as she didn't have a weapon in her hands.
Meanwhile, back at the beginning of the above case, when she got released she filed for protection over in family court from me and included our son. (It was all about blocking my parental contact of course.) First thing, the court excluded our son. Second, since I already had possession granted in the other court's TPO, this TPO only told me to stay away from her and not contact her unless it was about our child. She had entered on her petition that there was another case pending in the other court but I have no indication the magistrate looked it up. Family court asked one question before issuing the temp order, "What are your work schedules?" With that minimal input you can guess what happened. She was declared temporary custodial parent and awarded majority time. I got typical Dad EOW. At least it was a full 3 days on alternate weekends, some dads only get a 1-2 days at the beginning.
The court ignored her initial claim for protecting our preschooler, she said I had let him tip over his bike at the park and injured his elbow. It healed in a cast for a while but there wasn't even a scratch. At the first encounter in family court, later to become my "home away from home", teh CPS rep stood and stated his agency had "no concerns" about me.
Well, she was still trying to make me look worse than her so she continued making allegations every few months hoping I guess to have some claim to wave around at the next hearing and especially when she got triggered or did something that made her look bad, each one slightly different and of greater severity. CPS looked at each but never did side with her. Even though they pretty much "got her number" they still investigated each one in case this time it had merit.
Eventually the unsubstantiated reports can weaken credibility. That's what happened after a few years with my Ex. It was a couple years after my two year divorce and I was seeking full custody. In the Change of Circumstances decision from the court it noted many points and one paragraph noted that my ex had made an allegation during one of the professional's interviews but no one even bothered to ask me to defend myself. She had made an allegation of DV supposedly from years before but I still got custody. They may as well have made it a footnote. That's how low her credibility had dropped. But it took years to build that history with the court and professionals.