[gmu3]

It isn't possible to create a database storing all the possible tones a non digital instrument can make.

[cyberferret]

They are possibly not going for the individual tones, but rather taking a range of impulse responses (IRs) plus the original timbre. From that, they may be able to digitally reproduce the sound - or else use an ordinary violin, and colour the sound with the Strad's IR to recreate similar waveforms.

[keithpeter]

Both harmonic and inharmonic overtones and a changing mix over time. Would be a big database.

https://www.pianobuyer.com/Articles/Detail/ArticleId/40/Digi...

Above reference discusses some of the issues for digital pianos - which are well-established and it is easy to find demonstration models in music shops.

[Thiez]

How is this relevant? The recordings only need to be good enough that a (trained) human cannot tell the difference.