(InB4 ‘How Funcom does X with Y in EC’, we know, you’re angry the game isn’t perfect. Take your sour soggy bottom feelz elsewhere.)
So… Silkwood giant spider is a wanderer, once she gets up the path of her spawn point, she is off on great adventures, to eat adventures and other mobs throughout the Exiled Lands. I have seen/paced her as far east as the shoreline, and as far south as the break of desert between the river delta and jungle biomes. She is also quite capable of crossing back and forth over the Cursed Wall to use off map terrain to get around on map terrain. Normally, this actually is not an issue, unless you build in the jungle near Silkwood. It is quite a surprise to have a massive spider suddenly emerge from beyond the Cursed Wall and start wrecking your thralls and base with ease.