Two tracks added:
-acf_tokyo246
-china_2019_fab (streams added to original config by shin956)
Each should work with various versions of the tracks. You can extract these extension folders into your tracks, or cut the rain fx data out of the ext_config.ini using a text editor, and paste it into your track's config file (whether it be inside the track's extension folder or in assettocorsa/extension/config/tracks/loaded. If the version of the track I used already had an extension folder, I've included the original config in a separate folder.