I think you'll have a difficult time finding any public-domain, SMF-format sequences for the FB-01. Despite its multitimbrality, the FB-01 seems to have mostly just been used as a supporting device in larger synthesizer setups, perhaps making the unremarkable arrangements that Sierra produced the best surviving examples of anything resembling complete FB-01 compositions or scores. I don't believe these soundtrack arrangements have been converted to standard MIDI files, but that could be done with a little bit of effort.
Beyond that, you might have better luck searching-out and converting some of the proprietary formats of IMFC and SFG-01/05-supporting sequencers. Likewise, it seems reasonable to think that some number of X68000 compositions could be converted for acceptable playback on the FB-01, notwithstanding the limitations imposed by the MIDI interfacing and interpretation of the latter, as compared to the bare register access of the former.
Sierra's native SCI0 support of the FB-01 requires that you manually disable the memory protection on the device to facilitate the uploading of the custom voice banks, due to a bug in the FB01.DRV driver. I recommend the use of ripsaw8080's modified driver instead, where this process is performed automatically, as per the original intent:
*START HERE* SoftMPU 1.91 - Software Intelligent MPU-401 Emulator
Today, the only King's Quest releases to support FB-01 music playback are the SCI re-release of I, and IV, and there are different methods involved in getting the latter to work, depending on whether we're talking about the 1.000 release, or the 1.006 release. Disappointingly, while Sierra did create an aftermarket IMFC driver and PATCH.002 file for King's Quest V, they neglected to write an SCI1-compatible FB-01 driver.
Since you're using an MPU-401AT, the following doesn't apply, but if SoftMPU is ever used in lieu of a hardware MPU-401 interface, make sure you're using version 1.9, which includes the necessary support for the large SysEx messages used by the Sierra titles. Similarly, DOSBox requires a larger SysEx buffer size, via custom build, when paired with an FB-01 for Sierra gameplay.
Finally, using the FB-01 with either a modern or DOS-based sequencer shouldn't be an issue at all, as most support the use and embedding of SysEx data.