I wanted the ground effects from Legion 7.1 as I already had the NODXT converted to wotlk, all I needed was the DBC files so I could use them in WOTLK.
This is the DBC from Legion 7.1 Ground effects Doodad and Ground Effects Texture converted down to WOTLK(3.3.5) so you can use the groundeffects from the Cata+ Expansions. I tested with the Lost Isle map which I converted with Adspartans converter and it worked.
If you convert a map down from Cata or Higher, and have these 2 dbc files in your clients DBFilesClient folder and your server DBC folder. The groundeffects for those maps that you converted will show up in-game without you having to edit anything.