Knowing how to use a sword or even recognizing what makes a sword a great does not make a guy a blacksmith. Perception might let you notice all the different parts and how they link together when you raise the hood of a car, but that doesn't mean you can put an engine together from scratch. Fine motor precision is helpful for following a template or working in a factory, but not creating something that's yours.
It's an average or hard check. Nothing a session's worth of XP, some tools and a destiny point can't fix for even a 1 intelligence character. A Jedi(or Sith for that matter) is expected to be diverse enough to handle a myriad of situations. Just look at the Jedi Trials in Nexus of Power. Having a character spend some xp to shoulder up a weaker skill that isn't a focus because they need to is not a system flaw, it's an opportunity for character growth and development.
I have a pilot in a game I GM who has started pouring ranks into medicine because he tried to bandage a woman and failed on a simple check like three times and he decided his character couldn't stand seeing people in pain like that. If crafting your own lightsaber is important to your character 15 or 20 xp into mechanics shouldn't seem like an obstacle.