Check with your manager about options for making bookcases.
b- alt+c to place one
//Torrenal
I can "construct" bookcases via alt-c, but far as the manager and workshops are concerned, they don't exist. I'm likewise unable to make playable musical instruments.
Bookcases are new to 0.42.X, so older saves will probably not have the raws to construct them. Most or all of the new stuff will be unavailable to old saves. I would guess some extremely careful raw editing might allow you to make bookcases, but there's probably a great risk you'll end up wrecking things if you try.
You won't have any music instruments either, and since they're generated during world gen there's no reasonable way to add them afterwards. The old (unusable) instruments will probably still the there, but still be unusable. Poetry and dance forms are generated during world gen, but since they can also be generated during play there is some chance it might be possible for your dorfs to be the first ones to invent any of those.
That's what I was afraid of. My fort has the ability to designate taverns,temples, and libraries. So far, I think they've been telling stories continually, but I haven't noticed any poetry or dance. Curiously, they have been using the taverns and temples with enthusiasm per version 42, even though I had to switch versions to establish the tavern appropriately. I was hoping that bookcases would likewise cross over since they also aren't unique artifacts made at worldgen.
I really like this fort, and I *did* put some considerable effort into that library space, so it's really tempting to try to edit them in (library things in particular.) Where would I start looking if I wanted to try?