Well, after trying some setups recommended on YT and watching some videos, here is my conclusion:
Check this video to understand what the settings do: (15) How to get the best Forza Motorsport Wheel settings. Now with Timestamps!!! - YouTube
And that’s my result:
The only interesting things are: FF-Scale, Steering Self Alignment, Mech & Pneu Scale. Everything else is icing on the cake without defined taste. Use at taste.
Steering Self Alignment - is the overall setting for the next two.
Mech Trail Scale - How much the wheel wants to go straight by itself / self-correct when tail goes away .
Pneu Trsil Scale - How much the wheel feels softer when in understeer.
And that’s it. On the Logitech, everything else just adds not very well-defined noise - wheel feels like grinding gear - that will add to clipping and you need to reduce overall FF Scale to not clip.
IMHO all the rest is just rubbish noise in the wheel that takes away from the information you want - at least on this wheel, i never had a direct drive wheel in my hand, there it may work better.
Vibration - this just adds vibration in the same way as it is done for controller - find it pointless.
Road Feel - some additional rattling from road - not well defined, even that it looks good and pronounced on the telemetry. - found no useful setting
Load Sens - adds force from the working. suspension. Another rattling, grindy feeling without definition - found no useful setting.
Center Spring - have no idea what this is good for
Damping Scale - wheel feel heavier - you may like this.
Dynamic Damper - how Damper behaves under load - you want to use this if you have Damping enabled.
Probably the G-923 just has not enough force / force fidelity to make something out of the settings for Road Feel and Load Sens. And if you use those settings, you need to lower Self Alignment or those forces will be clipped out in some corners.
EDIT: After driving this way some time, this setting even gives you curb / road bump feedback if they are pronounced.