One, prison may be a bridge too far. There are already laws on the books against false informing - but the punishment varies from state to state. That may be encouragement to pass national model law, analogous to how Roe v. Wade was finally addressed by the Supreme Court.
Yah, allegations require prompt evidence gathering, investigation, forensic examination of any physical evidence, thorough careful interview of the accuser & the accused, & any witnesses - all the usual benchmarks of a good investigation. If the charges can't be sustained, it may simply be for lack of evidence, indeterminate evidence, or too much time has passed & any evidence & memories have dried up. Forensics have gotten better & better, but memories still fade. But yes, if the investigation concludes that the accuser deliberately lied, then charges are in order. But I doubt that the charges will be as severe as those for carrying out criminal sexual assault.
& it's not merely stories of sexual violence - any assault counts as violence, even if it's just touching without permission.
Trump wouldn't be my go-to guy on any kind of criminal charge, let alone sexual assault. Didn't he essentially plead guilty on the infamous tape where he's discussing grabbing women by the pubis with relative impunity?