Use of special characters in any field during ACH/EFT donation leads to ambiguous error; Error message needs improvement

Public-facing error message on the donation form: "Error: There was a problem encountered while processing your donation." (Image - https://c.na31.content.force.com/servlet/servlet.FileDownload?file=00P37000005Vuxk)
Error Code in a declined transactions spreadsheet report: "runTransaction: Luminate Online Error: www.ezpaycenters.net: unknown error"

Our ACH/EFT processor, Accepta (http://acceptapayments.com), said the error was caused by a special character being used in one of the donation form's fields; for whatever reason, this causes an error when attempting an ACH/EFT payment, but does not for credit card payments

In our specific case, the donor resided in Mexico, and "San Andres Cholula, Puebla" was put into the City field. The comma there was what was causing the error, so by removing ", Puebla", we were able to process the gift.

The reason this wasn't apparent was because...
1) neither the public-facing error message nor the admin transactions reporting error message made mention of special characters (or ANY specific issue at all)
2) when the donor previously included a comma in the City information for a previous sustaining gift by credit card (rather than EFT/ACH), the information was accepted as is and did not produce an an error message.

If allowing special characters within an ACH/EFT transaction cannot fixed outright, Blackbaud and Accepta need to collaborate to ensure the error message generated by this issue is much more specific. If the error message served were more specific, this could have been resolved immediately without needing to contact either Blackbaud or Accepta.