So I prefer single player racing and I was wondering if AI can still be trained

No. Forever ago the training AI (which were slow) was replaced with a new AI system. We can see with the mods that it is able to quickly iterate an optimal race path in a short period (30-40 seconds)

Quote from subUwU :

So I prefer single player racing and I was wondering if AI can still be trained

I don't know how the latest version of the AI is coded. But it looks like the AI times are improving a bit race after race, to a certain extent.
If your problem is that the AI is too slow in your single player races, you can easily make it faster with the mod system.

yea but I also want to improve their spatial awareness and maybe get them to do some overtaking

For spatial awareness you won't get anything that way. The flaws of the AI remain the same, even are amplified by the increase in speed.

But with faster engines, the AI behavior changes a little. Bots are much more aggressive and attempt (and sometimes succeed ) more overtaking. Races against the AI are less boring. You are no longer alone on the track in the first laps.

It's not entirely satisfactory, I agree. It's just a way to continue playing solo without falling asleep.

Quote from subUwU :

yea but I also want to improve their spatial awareness and maybe get them to do some overtaking

get coding

If you are passionate about AI programming, I recommend reading this topic.

https://www.lfs.net/forum/thread/63807-Artificial-Intelligence-in-Racing-Simulations-Project