You say this account has a custodian. That usually indicates that the beneficiary of the account does not have physical control of or access to the money. If your wife had physical control of the funds in 2017, then a FBAR needs to be filed for 2017. This is true even if that "access" to the funds was possible through the custodian. You may also need to amend your 2017 tax return (if already filed) to report this "foreign asset" to the IRS, if it wasn't resported on the originally filed return.
Otherwise, if your wife did not have access to or control of the funds in 2017, then it was not yet "gifted" to her, and need not be reported at all.
