When a molecule is proposed by a model rather than by a chemist reasoning from known biology, two separate questions arise. They are often lumped together as 'the black-box problem,' but they are different and they fail for different reasons.
Explainability asks: can anyone say why this molecule was proposed? A transparent design process leaves a chain of reasoning — this target, this binding site, this property, this trade-off. A black-box process produces a molecule without a legible reason. The molecule may still be excellent, but the developer cannot explain the design choices, and a regulator cannot evaluate whether the reasoning was sound or lucky.
Reproducibility asks: if the same input is run again, do you get the same result? This is a practical auditing problem. If a model's output depends on random seeds, on a specific version of the software, or on data that cannot be shared, then no one else can regenerate the result. Regulators cannot audit it, and other scientists cannot build on it. A result that cannot be reproduced is, for regulatory purposes, not a result at all.