The result in unreal, even at 8k - leaves very blurry textures on the landscape and not really suitable for play. My original intentions were using this as a base texture, then applying additional textures/materials on top of it to detail the landscape further.
Do I just need to render the textures at an even higher resolution? If so, or there’s a better way to solving this problem please let me know. Any help is appreciated.
The use of macro textures would be the way to go. This will give you more freedom regarding the level of detail, aswell as more control over the final output.
Take a look at the grass/moss material that comes with the starter content for some inspiration.
I think you may want to avoid using World machine generated albedo texture for your terrain. That would only look good from considerable height (kinda like you see it in world machine). For an FPS perspective you need high res tiling textures and then use all sorts of blend maps to break up the tiling pattern these may cause.