Well then, after creating a new campaign, waiting lots of lots of days and running around to many cities. I can conclude that the problem with crossbows is a bug that some players, including me, seem to have then. Because I can't find ANY crossbow anymore. I do believe I've seen others reporting similar stuff as well that they can't find crossbows at all after that patch.
But it's good to know that they are suppose to exist at least and that it isn't something they just haven't added yet. So thank you very much for that info! Thank you very much as well for the information about the wood workshop, it'll come in handy later!