Paths are an integral of the game design; designing a civ in Civ VII without figUring then out is like imagining civs in civ VI without making sure they have an actual still-existing language they can use. The fact that players can work around them by using.
This means that some regions will have more obscure choices in some eras, and be missing some less obscure ones, or that we will have cross-region paths. That's part of the design,
I don't buy one civ leading to a dozen as something that will happen. I'm fairly sure I heard the devs make reference to not wanting to overload new/casual players with evolution paths, so I think we can firmly put 12-path scenario out of our heads.
And yeah, Goth and Phoenicia/Carthage leading to Spain works, and so does Rome (but as above, I don't see Rome getting a dozen path so it may well lose some of its current ones as new civs get introduced that need Rome more). The problem isn't lack of good path into Spain. It's that anything that's good for spain is equally good for portugal, anything that is good for Portugal is equally good for Spain, and anything that's good for both is equally good for Franks, Normans, Italians, Dutch and half a dozen other equally important places.
Makes it hard to come up with spearate portuguese and Spanish lists without blocking other civs, while still keeping the number of path reasonable (again: sorry not sorry, I don't believe the devs would do 12 path civs).
My current thinking is to move the Franks back to ancient and make the proto-HRE civ the Carolingians instead of the Frankish Empire. Then the Goths can cover Mediterannean Germanic people (Iberia, Italy) and the Franks more the France-Low Countries-Germany centered germanic roots. And the Norse can still norse it up of course.