Are questions along the lines of
what is the impact of law XYZ on crime/wellbeing?
allowed?
I think such questions are very interesting, but I am not sure if they're specific enough to law, or simply the impact of a law.
I would vote to close the question which you asked as a call for opinions. It must be re-written so that it is actually a question about the law and which has a factual answer (one that is true or false). For example "Did Act 37 of 2012 reduce the {violent crime / unemployment} rate in Elbonia?". Questions about "wellbeing" are always too vague an opinion-laden to be on-topic.
Are questions about crime statistics and the impact of law(s) allowed?
Yes. Both aspects pertain to the on-topic item of "Historical legal applications". In fact, empirical research is showcased in several law journals. Two examples are about Second Amendment Underenforcement and the application of Hypothesis Testing to Title VII Cases.
Although on topic, that type of questions is unlikely to elicit answers. That is in part because the combination of fields is quite narrow and of little-to-no interest even to us who have background in and/or exposure to both mathematics/statistics and law. Additionally, it seems to me that the percentage of legal issues on which empirical studies are available is relatively low.