Going with the idea that the dagger doesn’t explicitly say the Wayfinder’s location, you would have to cut two lines already:

The location of the Wayfinder has been inscribed upon this dagger.
I know exactly where the Wayfinder is.

So I think it works better that 3PO knows exactly what it says, and knows it’s the clue to find the Wayfinder that Luke was looking for. But, they’re instructions, not a precise location, so 3PO can’t just punch it into the navcomputer himself.

EDIT: And I see your point Jar Jar. To be fair, Rey doesn’t really hold it long enough to know how it works, so I don’t think the whole journey is undermined by the change.