If, as I have, you set d_init items as follows:
[AUTOSAVE:SEASONAL]
[AUTOBACKUP:YES]
[INITIAL_SAVE:YES]
(...or a meaningful variation on this set, but that's how I invariably have these configured...)
...then you should have what you need without too much fuss, at least for Fortresses, without doing the (trivial) manual world-directory copying.
Although I often do that too (a side effect of backup seasonal saves, which means I tend to stuff in a .zip once they're superceded by at least an in-game year's additional play, just to neaten things) including doing a post-worldgen manual copy of the unplayed savedir so I can consider playing (unconnected, but sharing the 'history') multiple versions of a worldgen, including an Adventurer embark or two alongside the Fortress(es) I tend to waste most of my time on.
If I was more inclined to check Legends info (very interesting, as is the way the Steam-release is apparently to present this info, afresh), naturally I would just pick up my habitual copy of the save for legends-viewing.
It would break the fourth wall though. Learning things that your Adventurer has to work at to learn 'naturally', even if that's just happening to talk with the right people. Not really an issue, given there's no such thing as cheating, as long as you realise that any such easements (and additional personal-challenge restrictions) are just how you play your game. My own practice (for which I might make use of the multitudinous backups) is a hair-breadth away from save-scumming, though it's mostly that I mighf take the (further manual copy I make as needed of any) backup copies 'for a ride', to retrospectively try some throwaway replay, but once I've done that I generally mothball the rerun-save and return to the Prime copy without the mini-megaproject/whatever, or any in-game experience of swimming down a river to the ocean 'just for fun'.
But I can see why there might be good reason for limited (to Tarn's general gameplay focus) extra info more easily grabbed without any of the above. As mentioned, it seems the Steam-release might be giving you an expansion on the current infograb opportunities, already, presumably with these written-in limitations. But also there's no reason to believe that whatever purpose you might currently to scum for (or how you prepare for the possibility) could be more restricted in future.