Could you be more specific about what you are trying to do? I'm not at a computer, what does the file do? Did you make a mod folder and place a copy of the file there, did you add the config.ini file in the mods folder?

Ok, I want do replace 'simconfig.txt' in the data folder.
I already created a mod folder, with the data folder and new 'simconfig.txt' inside.
And i added the config.ini in the mod folder.
I can load the mod, but nothing happens, as if the files isn't replaced.
When I edit the actual file, it works, but not as a mod.

I would like to do the same with data/simulation/tasks/conveyor_crossover.ini so it can be replaced with a crossing that includes a turn table as cars can change direction on this crossover conveyor. So simply stated the question is:

How can we replace/overwrite a default game file?

Looks like it never reaches the modded simconfig.txt and only uses the vanilla one.
Might be the same thing as with the translation files. If you try and change a value that allready exists in the vanilla file it won't work but adding new information to the file does get picked up. Looks like the code is looking for vanilla files first and only when it doens't find the answer there it goes and looks at the mods. Should be the other way around.

I'd like this feature aswell. If the mod has a file use that version instead of the default version. .csv files excuded.

Just create a backup file and place it on your desktop. Then modify the current simconfig file the way you like it. That's what I did. I notched AI research duration from 0.9 to 1.5 in order to balance better the game. It works with all saves as well since I noticed a significant decrease in AI research. No longer am I getting pop ups every minute that AI researched a new technology. In case your game crashes, you can always put back the default file you saved on your desktop.

The point is I would like share my work but that is not posible if I can't modify the original entries. At least not in all cases.