-tip
Hi, Chhonos.
First of all, are you certain the clear top coat is lacquer? No offense intended, but many people refer to any clear finish as lacquer or varnish. Not necessarily true, as there are a whole bunch of clear finishes in use these days. Lacquer is just one of many.
Hopefully, it is lacquer. If so, touch up and refinish are easy.
To test your finish to determine its type, dip a Q-tip in lacquer thinner (not paint thinner or mineral spirits). Rub the thinner on on the finish in an inconspicuous spot, eg. the backside of a leg or apron. If the clear finish softens and comes off in a minute or so, then your finish is lacquer. If it is unaffected, then it is probably conversion varnish or possibly polyurethane. Polyurethane is not real popular in production settings because it stays wet for hours. Lacquer and conversion varnish dry almost immediately, therefore, they are popular in the furniture industry.
If your finish is lacquer, it is probably the catalyzed type as opposed to the older nitrocellulose variety.
If the scratches on your table's lacquer top coat are not cut down into the color, then sanding and a couple of new coats are a snap. New coats of lacquer dissolve into the previous coats and create a great bond. Generally, it is sprayed, but there is at least one brand that can be applied by brush.
Lacquer and shellac are the most friendly finishes to recoats. All other types can be very problematic due to difficulty of adhesion between the original coat and recoats.
Regarding your question of the value of the proposed refinish......a good refinish will put the rails back in like new condition, versus the worn condition they are in at present. The potential sale value of a pristine Cromwell will be much better than that of a scratched and well worn looking table. But, in the end, the actual dollar amount is determined solely by how much someone would give you for it.
And lastly, regarding your woodworker's insistance on knowing the exact brand of lacquer, for the most part...lacquer is lacquer.
Hope this is useful to you.
Joe