I forgot to mention I also found this video where someone made a rear shock saver link for an odyssey. I will definitely do this to my odyssey now that I know it's possible.

It looks like the skid plate would have to be removed or cut to fit the new bracket, but that's not a problem

https://www.youtube.com/watch?v=rykJHQ3SGeI

Give it up, the keyway is mushroomed. In my opinion you're done.
This thing has to be accurate because of timing. Some members here run an offset key to advance the timing but it is very little offset. I asked for a drawing in a post I did on it but nobody has supplied one.
You could de-rivet this thing and play around with fixing the keyway but it would be very time consuming. Also it looks like the taper is scared up as well from the key rolling over. It might be better to get a new flywheel. There are lots on feebay for $30 to $50 so not really worth fooling around.
CO



Looks like he did a very nice job on that.
I think the chain idea is a lot simpler and easier. Just my opinion.
CO

EDIT: If the key rolled in the flywheel it rolled on the crank. So what does the crank look like ??

Don't know why it's upside down. That edge on the right side of the key way doesn't make me feel confident

That's what I suspected.
I don't know what you mean by the "right side" of that picture, but based on the way the pic is posted I see some flaring of the keyway on the bottom side of the keyway in that pic the way it's posted.
It doesn't appear to be that bad but ANY flaring in not good. It most likely swelled the shaft a bit in that area and you may have to GENTLY file the swelling down a bit or it won't hold a new flywheel because the taper will be a poor fit.
In my opinion I would try a skillbilly fix. You will need a new flywheel based on what I saw there. Then fix the swelling in the crank keyway with a file. Then I would mix a very small amount of JB Weld and wipe a thin layer on the damaged area. Then install woodruff key and new flywheel. During the install of the flywheel you will remove the socket from the torque wrench, put it on the nut and smack it with a hammer (use common sense). Then re-torque. Repeat.
You must allow 24hr cure time in a warm shop.
CO