My guess is that how “finished” the bore is doesn’t matter much. But I am just guessing. There are things on the net about making recorders, such as:
Bernolin, talking about WOODEN recorders:
https://www.bernolin.fr/english/making.htm
An iteresting thing about this Bernolin article is it gives you a good idea of why his resin recorders (which are NOT mentioned) are so much cheaper. All the work that has to be done with WOOD is pretty amazing.
Another thing, might be good; you can read if you want (it IS in English):
http://www.mcjbouterse.nl/handleiding-fluitenbouw/handleiding-inhoudsopgave-Engels.pdf
From Dolmetch:
https://www.dolmetsch.com/recorderoil.htm
From this, I get the idea that the finish on the inside of the bore is mostly related to how the recorder withstands the constant wetting and drying out, not much about how it sounds.
An article on the Evolution of the recorder’s bore:
http://www.flute-a-bec.com/evolutionpercegb.html
From this, I get the idea that it is the SHAPE (conical, more of a cylinder, etc) of the bore, and the sound holes, that determine how it sounds.
Again, I do not think the finish of the bore is related to how it sounds, partly because I haven’t seen anyone mention it in the above reviews (although I only skimmed them). I think it only SEEMS as though a rougher bore might be more mellow. But this is just my uninformed opinion – I have a lot of these! 😉
