That is an interesting idea jarbear. It makes the dagger less of a way finder for the Wayfinder, and more of an independent tool. Though it might raise questions of why he didn’t use it to find Rey before leaving Jakku.
EDIT: Maybe she could hear whispers of “Endor” and “Death Star” rather than literally seeing it. And Rey didn’t know how to use it when she first picked it up, but I can see the fear of that not being explicit.
Yeah, not a perfect idea and doens’t cover everything, but is that question worse than “why a dagger that points to something that points to something?” Hahaha!
But in all seriousness, I get that it may not solve everything, but maybe with some vision stuff it may help. Without 3P0 translating it, she/they wouldn’t know it is significant for Rey to use. She also would have to acklowdge she may need to give in a bit to find the Wayfinder with the dagger which she wouldn’t come to that conclusion without the translation.