All community modifications to the game should be put in your ‘community folder’; the sim loads content from here after the main load of the sim is complete. When we create mods/addons etc they use the same folder structure as the base sim and simply override the sim’s files.
This system allows you to overwrite the sim files in a safe way rather than update the core files which is a one way trip to having to redownload the whole sim.
The reason we ask users to remove items from the community folder is to check that there isn’t another mod that overwrites the files you are modifying as well. For example our G36 Bonanza Improvement Mod for a long time was not compatible with Robert Young’s Turbo Mod as we both amended the same files. (which we’ve fixed now)
The sim works with alphabetical loading order as well, so files with z as the first letter will load last.
When trying to diagnose an issue we’ll quite often ask what other mods you have to try and understand if this could be linked to your problem. By removing all other mods you rule out that problem.
As Asobo & Microsoft work on the sim they refactor code, when updating you should put the folders & files in the community folder in a backup location and allow the sim to load ‘fresh’ without any changes.
This ensures the sim works first, quite often there are things that addon teams have to change to get their mod to work again.
Hope that helps 