Definitely not a luthier here, but I've got 40+ years of woodworking hobby experience. Consider this:
This has been said, but not followed up on.
If the substrate of the finish (the rosewood) really is soft, it will be essentially like putting a nice hard finish on a sponge. If you press hard enough, or over a small enough area, no matter what kind of thin layer you put on it, eventually the finish will crack and break down unless it is really flexible. Or unless you get it really thick. And even then they can separate. So the property you need is toughness, not so much hardness.
I have used a product on older, partly rotten wood that has a strong penetrating carrier and a very hard resin component that gets drawn relatively deep into the wood (like maybe 3/8" into old floor joists): Minwax High Performance Wood Hardener. It turns the surface into a plastic rock; it's actually hard to sand and machine. Basically you've made something like carbon fiber or fiberglass, where the wood is the fiber part.
Ideal? No, there are drawbacks.
The wood will expand some, and it really darkens the surface. Both not good in this case. But I don't know anything else like it. It's also got ketones (Acetone) as the carrier, rather nasty stuff; don't snort or taste it, and limit breathing the vapors!!! Here's a link:
Minwax High Performance Wood Hardener - Harden Wood | Minwax
The other issue is that rosewood is an "oily wood", and by it's nature it doesn't allow most things to penetrate very deeply. Maybe bleaching and alcohol beforehand would lessen the impact of darkening and not penetrating, that would have to be tested on a scrap piece, but I wouldn't get hopeful.
Just my two cents; and there may be other products out there that are similar but more suitable.
Edit: It also instantly dissolves any plastic it comes in contact with, things like inlays and side markers may come off, whatever it touches is pretty much permanent.