Saying you're confused by the software indicates that you've had very little experience with reimbursements. This is a high risk topic and you should consider engaging an experienced advisor to help you get through the project.
If you reimburse even one account, you will have to respond affirmatively to your regulator's next pre-exam questionnaire. That flags TIL for additional review, opening the door to even more trouble. It's good business to get a second opinion before volunteering for this painful treatment.
If you reimburse too much, you don't buy any greater protection and there's no way to get the money back from affected customers if you later discover your errors.
If you reimburse too little, you don't cure the violations and stop the civil liability under the TILA. In addition, your regulator will probably detect the underpayment and order you to reimburse more. Correcting a correction will surely damage your reputation in the eyes of affected customers.
Your greatest risk is that the underlying cause(s) of the disclosure errors are not identified and fully excised.
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...gone fishing.