I've seen this question a couple of times now in the last month or so. There are a few potential penalties relating to CRA, but not as many as you might think.
First, a bank rated less than Satisfactory must include in its public file, a description of its current efforts to improve its performance. That description must be updated quarterly. This might be addressed in a Matter Requiring Attention in a report of examination, but failure to raise performance to at least Satisfactory carries no penalty, per se. This could theoretically go on ad infinitum, or nauseum, depending your point of view, and depending on if your bank has corporate aspirations.
If your bank desires to be corporately active, i.e., wants to branch, merge, or do any of those other things that require you to apply to your friendly regulator for approval, then your CRA performance comes under a little more regulatory scrutiny, as CRA requires the regulators to consider a bank's CRA performance in such matters. So, the second penalty is that regulators can deny or conditionally approve an application in the face of poor performance. Conditional approvals will extract some bank commitment to take some specific steps to improve its CRA performance. If you don't apply for any corporate actions, this won't come into play. You can effectively thumb your nose at CRA, if you choose, although that's not something I advocate, as it can invoke the third penalty.
The third penalty comes from reputational risk. With the CRA rating being public, it's possible that customers will decide not to do business with you because of your CRA rating. Community groups or news outlets could drag your bank's name through the dirt, drawing more public attention to your performance, thus besmirching your bank's name and reputation. Some states have laws prohibiting banks with less than Satisfactory ratings from holding public deposits, too.
Beyond that, there aren't any other penalties. Congress specifically prohibited the federal banking regulators from using their usual arsenal of enforcement actions in CRA matters, like cease & desist orders, formal agreements, civil money penalties, etc. So, enforcement is simply through the corporate leverage and the reputational risk. AR.