converting oiled walnut to "rosenut" color

The suggestion for bleach overlooks that fact it will raise the veneer Try the ethanol/water approach first, again on the bottom.

lightly sand-stain black
Black goes with anything
Rosenut looks like crapola

I would not recommend using bleach or alcohol. You could dissolve the adhesive that holds your existing veneer onto the base wood. If your veneer is over particle board you could wind up curling the ends and corners of the veneer. Or causing the veneer to separate.

If your speakers have an existing oil finish I would suggest products from DOF (danish oil finish). It requires detailed work and is labor intensive. How do you plan to protect the speakers in the cabinet and the guts of the speaker? I would empty the cabinet, noting wiring and even marking the screws.

Re-veneer.

A passing thought..If I put a coat of shellac(universal sealer over nearly any finish) on the existing veneer-finish it would seal it. This would give me control over how much of the gel stain to apply and allow me to back-up to a point where no gel stain remains on the veneer. I'd test first, but I believe mineral spirits doesn't dissolve shellac, but it does remove the gel stain.

hififile..I considered danish oil, probably what is on there now, and watco does have a cherry danish oil(I have some), but the color is very light and wouldn't be enough to get me to the rosenut color. I agree the ethanol might lift the veneer edges. Hard telling what kind of adhesive they used back in the 80's. The veneer on the corners right now are perfect.

I've done some searching on the web on how to do this and I'm not finding anything...not even when you start from unfinished walnut.