I should point to the recent case of Gian Gomeshi, here in Canada. Fired from his job (prominent public radio host) after several woman alleged that over the years he had engaged in violent (attempted) sex. (choking, etc.) the case IIRC was thrown out because it was shown that the women had lied about being in contact to compare stories before the trial. He’s still persona non grata in the entertainment community; that there was not enough credible evidence, given the tainted witnesses, to get a guilty verdict did not mean that he has/had a chance to recoup his reputation. The risk in suing for libel is that he then has to answer the accusations to a lower standard of proof than “beyond reasonable doubt”.
The trouble with actual criminal charges is, in the case of assorted varieties of sexual assault, it often boils down to he-said-she-said. Absent any physical evidence contradicting the competing claims, can you really take one person’s word over another’s as the only proof “beyond a reasonable doubt”?
But really, the OP points to the dilemma so many accused - not just sexual assault defendants - face. Canada had a spate of prominent falsely accused /falsely convicted in the news over the last few decades. You can google Stephen Truscott (sentenced to death at 14), Donald Marshall Jr., David Milgaard, Guy Paul Morin, Thomas Sophonow. All charged, at some point convicted typically due to police with a single focus and willing to “stretch the truth” to fit the crime… then exonerated. Some will forever be haunted by questions. The ones convicted and in jail at least had some compensation from the government when it was shown misguided policework was to blame.
But basically, if you are wrongly accused, you’re screwed.
To be fair, if the acquittal is prominent enough, like the cases I mention, everyone knows. The usual joke about crime reporting was that the arrest would be front page news and charges dropped later is on page ten. However, I heard about one case in a small town where the fellow was accused of murdering a girl. the case was so weak, the judge threw it out in the preliminary hearing and raked the police over the coals (Stupid stuff - like he washed the car, “obviously to destroy evidence”…7 days after the murder, 3 days after the body was found). That didn’t stop the police from harassing - when the suspect’s wife left him, the police were interviewing her the same day. They key piece of evidence in the hearing - a blood-soaked rag - DNA technology available 10 years later showed it to be what it was claimed, not the victims blood but a family member’s. but… that didn’t stop the fellow from having to leave town immediately after his release; there were people convinced he did it (he was seen in the area…) and all the lawsuits in the world are not going to fix that.
For that matter, at least in Canada interviews can only ask about “convictions for which you have not received a pardon”; I have heard that some US states allow a prospective employer to ask about arrests, even if no conviction. Therefore, any arrest regardless of the truth will forever taint your job prospects. the damage is done.
But, the short answer is - even a lawsuit probably won’t fix a reputation issue. Most accusers, too, probably don’t have the resources to pay you back for a legal fight, let alone pay any extra award for lost wages and lost prospects. Like everything else in life, sometimes fate screws you over. Just the same as if you are arrested, go to trial, and are found not guilty, nobody jumps in to reimburse you for your huge legal bill.