First, let me say that I agree that pointing out numbers that may seem wrong and not relating them to real life in some way isn't really useful.
However, stating this 53/47 difference as an actual weight (18kg) doesn't make sense. It's not like a 20kg difference on a 2000kg car is going to be worse than this 18kg on a 620kg car.
As far as percentage goes, you can't say each side is only 3% off (because each side is that far away from 50). 53.5/46.5 makes one side 15% heavier than the other.
The free radical (haha... no pun intended but I'll take it) we got in 2017 had a 49.4/50.6 split on the RHD version, and a 56.1:43.9 split on the LHD which reportedly caused quite some braking stability issues. I believe it was fixed in a later update but I haven't checked recently. That RHD balance is very similar to the example figures given for weight distribution in the SR3 XX user manual (50.7 I think I calculated).
The current weight distribution seems less balanced than you'd aim for. No doubt some chunkier drivers (or some extra light ones) might require either some car adjustment or just live with a worse balance, but presumably the car is designed for a certain weight of driver and will be fairly close with that, and you'd think that's what we'd get in a game where driver weight is an arbitrary figure. But, it's also possible the current distribution is based on reality, something I guess only a dev can confirm.
What am I saying? There's no real value in talking like this weight imbalance is either the end of the world or is completely fine, unless there's some specific reference that backs it up. If we don't know exactly what the real car that's been modeled is, we don't know if this is wrong or not. I note with interest that the post starting this talked about the car being off-balance but also said that 50:50 would be impossible with the driver on one side. So it's obviously easy to make assumptions.