Linux kernel is shared among all distros (fedora, ubuntu, etc), but the many configuration options (kernel, alsa, jack, pulseaudio, pipewire..) could be the issue here.
Nowadays audio just works out of the box in linux, but this is an advanced device with non-standard options, it may need custom config.
I would invest time to learn but I would first need to know if someone managed to get Babyface Pro IN3/4 signal to a linux computer via USB in CC Mode. Maybe the USB CC implementation of the device just doesn't allow it.
From the manual I don't see IN3/4 mentioned:
The Babyface Pro provides the iPad with the professional analog I/O connections it lacks. Superb microphone preamps, in addition to professional balanced line outputs, and a hi-power
headphone output that excels with both high and low impedance headphones. Plus gain and
level adjustments, SPDIF and ADAT input and output, at up to 192 kHz and 24 bit. And of
course a Sysex capable MIDI I/O.
As a workaround, I tested TR (bass) to XLR (Ch1 IN) cable. Signal gets to usb channel, but really low. It misses the proper gain
(no -10dBv option).
thanks for the replies!