Main Roads WA have released their data under CC BY and have completed the OSMF waiver allowing us to use their data, we even have a background layer available in JOSM and iD out of the box.

In this case Main Roads WA have the name "Grimwade Road" however this doesn't necessarily mean we should go ahead and change it, instead best to check what's signposted on the ground and ask prior mappers for any background.

In OSM it's good practice to map what's on the ground (https://wiki.openstreetmap.org/wiki/Good_practice#Map_what's_on_the_ground) and therefore the road names in OSM may not always match in any particular government dataset, and that's okay and to be expected.