I'm sorry as I know this has been done to death but I'm after a quick yes or no.
I have a Jap console and the firmware is quite old now so I was going to load up Super Mario Galaxy Jap-ntsc as I think this has the latest update. Would this safe guard me against bricking?
Whats the benefit of updating the firmware?
it's far safer to update firmware via your wii than a game. but you can do it via game if you are sure it's the same region
As stated above....If you are 100% sure the game is the same region as your wii you can update without a problem.....