Practically everything is adjustable if you open the configuration. You can save different configs for different aircraft types as well. I wouldn’t expect much of a rumble effect for an airliner taxying to be honest but gear and speedbrake turbulence are definitely there. Try turning up the strength and “exaggeration” of the effects, the SWFFB2 feedback isn’t that strong and sometimes needs a bit of help.
If it won’t launch the sim please get in contact with me via the support email, I’ve heard this from someone else and would like to get it fixed.