Unlikely, since the system validates LTCs and the chances they would bifurcate the database into "essential to keep available" and "one way only" is slim. Also, keep in mind that what you see with the e-FA10 is just part of the MIRCS system which was originally, and primarily, designed to provide law enforcement support for the licensing process as well as dealer validation of licenses and entry of sales data.
The number of businesses that put critical information on internet connected systems is astronomical, and the consequences of systems we generally accept as "internetted" being compromised dwarf that of the FRB database.
Virtually EVERY major brokerage house has all accounts on-line and such on-line access gives the ability to execute trades and, in some cases, transfer funds to unaffiliated accounts. Ditto for bank accounts. And then there are medical records - it's common for hospital patients to use the patient access system to see their own lab results on a laptop before the MD stops by with them (convenient, since protocol precludes nurses from giving the patient this info, though it happens for some routine items). One of the largest credit card clearing houses allows the merchant to change the bank account to which credit card payments are transferred by entering it on-line rather than providing a paper document.
The real risk would be if the FRB did not use security equivalent to the banks and brokerage houses (which despite assertions that "any system is hackable" seem to be doing pretty well), combined with the fact that, unlike the private sector, the jobs of anyone blowing it on security would remain safe and the state most probably immunized against torts.