When making it I use 100% optimum grip for testing, so there should not be too much grip. And you can definitely feel the front losing grip as aero effects kick in at speed.The LX4 in LFS did struggle for grip as well in a similar way but it's a different sim altogether tyre wise so the details all feel different and they should as it's a different car in how it's made and simulated. Other than that I go by descriptions of people who drove it when fine tuning the details such as dampers, brakes, ... and rest is mostly data found or measured. A small change can have a quite noticeable effect on handling as the Cats are so light, of course it depends how sensitive you are, for me I can change dampers by 2% and notice it, or tyres tweak a value by tiny amount and feel what changed. It takes a lot of practice and years of making setups for many cars in sims, a time consuming thing to do but so worth it when the car drives the way you want it to for the specific track and session type. Some people can drive, some can make setups and fine tune the car, some can do both (to a certain degree) and that IMHO helps a lot be it in sims or behind a real wheel, being able to tell the mechanics what change do you want precisely for your driving style for a particular combo.
What really helped and made a nice impact on handling was adding the progressive spring rate for wheel rate based on changes of motion ratio (ratio between wheel rate and spring rate) as suspension moves up and down. The angle of spring on front is large and the MR changes considerably. If I remember right it's 9kN/m when leveled and around 10kN/m when seriously bottoming out, that's 11% gain in wheel rate. And this is done for both front and rear wheel rate and bumpstop rates (made available in 1.15). AC has no spring position or spring rates, everything is done at the wheel, everyone making any car has to convert all the values from where they are from into wheel position. This can get even more confusing when you are in game and it shows you wheel rate values labelled as spring rates etc. at least it used to, thinking these values are wrong when you do not know that these are all wheel based, meaning if you want to use real data in the setup menu you have to convert it to wheel based first as well. This was not the case with LFS I think and it had spring etc. positions and the data could easily be used without conversions. These conversions and moving suspension to get the MR change with suspension movement are non trivial, 3D geometry math, the 2D approximations you can find online are quite poor I've compared them and with the large angles as are on Caterham front spring they are waaay off.