KDFW is at the top of my scenery list, so I don't know what the problem is, unless there is a compatibility issue with FTX Global - I really hope that isn't the case.
As explained many times already on the forum, meshes DO NOT respect the Scenery Library priority. A mesh with an higher resolution will always "win" against any other scenery, regardless of its position in the Scenery Library.
If you correctly set the Mesh resolution and Complexity sliders according to the KDFW manual ( not less and not more ), that's all you can do from the KDFW side.
If you are still getting mesh errors, they are caused by a bug 3rd party mesh you installed.
A mesh having a nominally higher resolution than default, is not automatically "better". Default meshes are pre-processed around airports to be smoothed out and don't have any holes, spikes or bumps, which are usually caused by missing data in the original database, or by humps caused by the satellite antenna that will pick up things like buildings, trees, etc. not just "terrain".
That's why, an add-on mesh should be pre-processed a lot, in order not to create problems to airports, and there are products designed to fix such bugs, like the Airport Flattening Mesh, to be added to FS Global ( but it should work with any other base mesh )
http://www.fly2pilots.com/Cms/Ui/Pages/Products/MainPage.aspx?id=d3fca479-6c4c-465b-bd75-97445878ae48In brief, the problem doesn't have anything to do with KDFW, it's a mesh issue, that can only be solved within mesh products.