Krita looks like a program I would like to use, but I'm having some issues...
I'm on a mac (OSX version 10.11.5) and so I went for the latest stable release of version 2.9, as is suggested on the Krita downloads page. However, it seems to completely ignore any kind of pressure sensitivity in my tablet. It also has this issue where I can't see what I'm drawing until I lift the pen whenever I have the layers window open. Only then does the line appear in full, as it does show the beginning of the line that I'm drawing.

So I went and tried version 3.0 instead, even though it isn't stable. Here, I don't have any of the issues from 2.9, but it has its own issues:
It sometimes zooms out randomly when I finish a brush stroke.
Upon finishing a stroke, the very end of the line tends to not appear until I click somewhere on the screen.
When undoing strokes, I don't see the results of the undo until I either click somewhere else, or undo another stroke (which I then can't see that I've undone until I click somewhere else or undo again...)

Can these issues be resolved? (I don't yet know if I have other problems because these are just so significant that I haven't dived any deeper into the program yet.)

When we say that 3.0 is unstable on OSX we meant that Krita is still unstable and experimental on OSX in general. We're hard at work on fixing these bugs. In the meantime, you can try and see if toggling openGL in the preferences helps any.

Thank you, that did seem to solve the last two issues that I mentioned. It still seems to zoom out at random, but that's a little easier to have to deal with