If your return was already accepted, do not worry too much about it.
The IRS understands that clerical type errors occur.
If they have a question about the foreign bank account, they will send you a letter in 3-4 weeks. If they do, simply say it was a mistake and that should take care of it.
If they do not send you a letter, then they are not concerned about it.
Do not try to amend or send a letter at this point. It may confuse them or prompt a review of your file.
