Launching the game failed

The three files you mention above, plus steam.exe and ck3.exe , really should cover it.  

In the game launcher please set Display mode to Borderless.

IF that doesn't help, Install ALL these Microsoft modules:

Download Microsoft Visual C++ 2010 SP1 Redistributable Package (x86) from Official Microsoft Download Center

www.microsoft.com

Download Microsoft Visual C++ 2010 SP1 Redistributable Package (x64) from Official Microsoft Download Center

www.microsoft.com

Download Microsoft Visual C++ 2015 Redistributable Update 3 RC from Official Microsoft Download Center

www.microsoft.com

Download DirectX End-User Runtimes (June 2010) from Official Microsoft Download Center

www.microsoft.com (run dxsetup.exe after extracting from this download)

Add stellaris.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.

Also if you have FRAPS or the MSI Gaming App or Rivatuner installed, disable it as it clashes with this game.

If that doesn't help:
DXDIAG is a program you run from a command prompt or the Windows start menu 'run' dialog box (or 'search programs' in Windows 7 or later). After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.

Please attach your Documents/Paradox/Stellaris/settings.txt and pdx_settings.txt .
From your Documents/Paradox/Stellaris/logs/ folder, attach system.log , error.log .