Hi, yes, LFS supports only the DirectInput (DI) protocol for FFB. Xbox controllers work with XInput (XI) so you can't enable FFB in LFS for such controllers out of the box. Logitech gamepads like F510 and F710 are natively supported once switched in DI mode.
There are some 3rd party emulators that can do such conversions, what you need is to emulate an XI device into a DI one, not vice versa. There is one such program, although somewhat risky but you may give it a try. It's very nicely documented, so I suggest to do some reading first. Downside is that creator is Japanese and the program is in Japanese, but you can use google translate for the webpage.
https://sites.google.com/site/0dd14lab/xinput-plus