Dave
Regarding polish.....Goddards is good, I use Pledge, to be honest almost all the commercial stuff will work. Manufactures of wood polish products would have you believe that you must polish furniture to protect it and regular polishing is necessary for proper care of the finish. But when you cut through the hype, people apply polish to make the finish "shine" more. A well applied varnish finish over veneer (your case) does not need anything applied to protect it.
Your original question was "anybody know how to buff that nasty scratch out". What you have learned here Dave is that you "should not" try to buff the scratch out. In doing so you risk cutting through the entire varnish finish down to the wood. Yes, you would have "removed" the scratch but this would leave you with a major refinish job on the entire surface.
Just hide the scratch as you propose, put a coat of polish on the entire speaker to even out the appearance and call it a day.
If this is not good enough then send me an email and you can call me on the phone and I'll give you other options.
For what it's worth I fixed a scratch on my Vienna Acoustics Mahler speakers(rosewood veneered, gloss varnished)using a wax stick, touch up pens and Pledge. The scratch is still there but you would have to know where to look to find it.
Happy Holidays