I'm sorry to hear that. But I have no idea how an installation would take 3 hours, the issues you mention are not related to the mod. The mod has been out for over 2 years with no issues. There must be some issues with your base game installation or system setup.
The launch via set launch options works perfectly fine. Or you can just launch via the bat file but it's not recommended. You can even see this video how it is launched via the bat file https://www.youtube.com/watch?v=3SMM...=CelticWarband