After more than a month of testing and learning, as I mentioned earlier when thanking Dundarrion, my electric cars, trains, carriages, and the passengers inside the vehicles can now be generated properly.
I didn't go to see the chickens; wild animals generated. I had already solved the issue before I discovered the problem, because my issue was that passengers in trams, carriages, and trains were not generating properly.
I couldn't be bothered to wait for the train in Saint-Denis. However, when I tested in Saint-Denis, I was able to see trains, trams, and passengers inside them all at the same time, and this happened while I was riding at high speed.
In the countryside, while I was at Emerald Ranch station, playing cards, trains came by every few minutes, and they had passengers inside.
The simplest way to test, as someone mentioned earlier, is to turn yourself and the horse into memory overloaders. I used the "John and Arthur Get Tattoos" mod and the "WhyEm's DLC" combination saddle and horse mask.
I deleted all the clothes and weapons from WhyEm's DLC because I don't use them.
I don't use high-end material mods, and my monitor is 1080p, so I can't see any difference when using them. The only mod I noticed any difference with is the Blackwater Terrain Textures Overhaul.
I feel that only this mod truly improves the texture quality of objects; the others just increase their size without any real effect. In fact, on my monitor, they make the game look more artificial.
Now, let me explain my solution. I’m not a programming expert, I’m just an ordinary player who loves this game. Maybe it’s a dumb solution, but my trams, carriages, and trains with passengers, both in town and in the countryside, are now generating normally.
First, as mentioned earlier, the texture files like YTD are the main cause of generation issues. I don’t use many texture mods, just the two I mentioned, so I’m like a walking memory overload, haha.
To drastically reduce the texture size, I reduced the "John and Arthur Get Tattoos" texture to 1024. For the WhyEm's DLC horse mask, I found and used the original YTD file from the game, which has a small file size but still decent quality.
The combination saddle from WhyEm's DLC isn’t found in the game, so it’s probably something custom-made. I could only find the layers, which had a resolution of 1024, but I reduced the combination saddle texture to 512.
I also added normal maps, lighting, roughness, etc., and the quality is still good. Even though I reduced the "John and Arthur Get Tattoos" texture to 1024 and the WhyEm's DLC saddle to 512, there seems to be no visual difference in the game, though I’m not sure if someone with a 4K monitor would notice a difference.
The "John and Arthur Get Tattoos" texture was originally 4096, so I tested three versions: 512, 1024, and 2048. The 512 version was the most stable, with no generation issues at all. 1024 seemed to be on the edge.
If I replace the WhyEm's DLC combination saddle with a 1024 texture, passengers don’t generate, but sometimes they still do. It’s intermittent, sometimes passengers generate, sometimes they don’t. Overall, there’s a 60%-70% chance that passengers will appear. I still use the 512 version because there’s no noticeable difference in quality.
Next, let’s talk about file replacement vs. streaming methods. I tested file replacement and it seems to have some effect, but it's not very significant.
With the streaming method, I can only use the "John and Arthur Get Tattoos" texture at 512 and the WhyEm's DLC combination saddle reduced to 256. However, using the file replacement method, I can now use the "John and Arthur Get Tattoos" texture at 1024 and the WhyEm's DLC combination saddle at 512, and the generation works properly.
Increasing the resolution further causes generation problems.
As for the animal generation issue, I’m not sure if anyone experiencing this problem is using the "Improved Wildlife ALPHA" mod. This mod has a lot of errors.
It drastically changes the animal generation radius and the detection scan frequency settings. For example, I saw that the original animal spawn range was 200 meters, but it was changed to something like 5 meters — I can’t remember the exact number.
Some of the detection scan settings were also changed from scanning once every second to scanning once every 0.000001 seconds. The generation priority weights were also massively increased. I believe a maximum value of 1 should be 100%, and anything larger doesn’t make sense.
If you have this mod installed, or similar files, try uninstalling them to see if it helps.
I’d like to thank everyone who helped me, whether I’ve mentioned you or not, for helping me solve this issue. Thank you!