I signed up to share this, as I know many others are still having an issue with the game not launching.
Give this a try if you're still having an issue:
Navigate to \programs (x86)\steam\steamapps\common\TOTALWAR Warhammer directory.
Next, double click on the Warhammer application within that folder. When I did this, I was given a couple error messages that did not pop up when trying to launch from the launcher. In this case, I was supposedly missing some DLLs for Direct-X.
Next, go to https://www.microsoft.com/en-us/download/details.aspx?id=35&nowin10
and download the runtime executable. Run that. It'll go through all the distributables for direct x up to this point.
Once that finishes, give it another try through the launcher. This resolved it for me after trying all the other fixes listed so far.
Cheers, and hopefully this gets you all in game!