I would like to restore a 1946 lane coffee table to the original. Was the original finish lacquer or shellac?
Even if you use various tests (solvent sensitity, scraping) to determine what a piece of vintage furniture currently has on it that doesn't mean it's the original finish and even if it were it doesn't mean you have to use the same thing.
I think you should choose what to use now based not on what was original, but on what would work best for the piece for you, today. And for many that won't mean lacquer.
Additionally, these days, unless you'll be using spray equipment and specifically buying nitrocellulose lacquer, working with "lacquer" means spraycans and that could mean any number of things are inside (e.g. acrylic-base, polyurethane, melamine). So unless you know for sure what your lacquer is you don't know quite what you'll be getting..... and manufacturer claims for product qualities aren't worth the paper they're written on.
What I'd use instead
Me personally I'd refinish in the best consumer-level finish available, and that's oil-based polyurethane varnish.
Oil-based poly is very easy to apply to a high standard (virtually foolproof in fact), is cheaply and commonly available, doesn't involve any spray procedures with all that comes with it1 and once fully cured after a month or so it provides superior protection to the majority of lacquers. And it has one further trick up its sleeve, as with all oil-based finishes it can actually make wood look better2. Even shellac, noted for how beautiful a finish it makes when applied as French polish, can benefit from having oil applied first to 'pop' the figure.
To loosely quote Bob Flexner, when you finish or refinish furniture part of it is making aesthetic decisions, so there are no absolute rules. People will disagree with what you choose regardless of what it is.
If you're worried about the non-originality aspect, there is actually a very long tradition in the refinishing trade of using something new, despite the reputation of restorers always choosing to match the original finish. Switches from raw linseed oil to BLO or a blend like Tung Oil Finish, synthetic wax polishes over the original beeswax-based ones, the use of a modern synthetic varnish in place of the original natural-resin one, even these represent a change in finish despite being somewhat like-for-like.
One additional point I'd like to add.
Strip, don't sand
Old finish should as much as possible never be sanded off any piece of furniture with any value (real or sentimental).
Sanding is, hands down, the worst way to remove old finish for a host of reasons but perhaps the most important is it has the greatest chance of doing irreversible damage to the piece. Chemical strippers are made for this job and although the work is undeniably messy and tedious, and almost always takes longer than expected, it produces a better end result.
1 No need for a solvent-rated respirator, no need for a spray tent or other clean room, no need to fuss with a spray gun's setting, no need to worry about whether a spraycan will spray every coat consistently, no worries about atomisation going wrong for the dozen or so reasons it can go wrong, no concerns about overspray.
2 On this side of the Atlantic purists are often dismayed that Ercol furniture is being refinished by current owners with various oil-based finishes (chiefly "Danish oil" and poly) instead of the original lacquer. But you know what? The wood often ends up looking better for it, 'richer' and less bland.