Some redwood is very hard, but most is not. Typically, the harder redwood is full of pitch, so it's not very buoyant, either, and probably wouldn't make good baits.
Reinforcing the screw eye holes with crazy glue, once you've run them in one time to cut the threads, is a good idea. I actually do that, and then brush some crazy glue onto the threads before I run the eye in again when I make a balsa bait, or any bait, for that matter.
I might seal the whole blank with crazy glue, like I do with balsa, just to harden it's surface. I use two coats with balsa.
I've read here a lot of people use propionate for their balsa baits, and that would probably work, too.
But, other that dissolving the bottom of a solo cup onto a workbench top when I put some acetone in it, I haven't had any experience with propionate.
I do so few balsa baits that I've never investigated it.