Remember how I mentioned that I like this layout, but the keys could be a bit closer together, and blamed the angles of the columns for them being too far apart? Turns out the columns are perfectly fine, the keyboard is just scaled up roughly 10%.
How did that happen?
Well, for designing the PCB outline, and for marking the desired locations of the switches I used Inkscape. I made sure all dimensions were correct in that program, using the handy unit switching options that program has. But as it turns out, Inkscape was recently updated on my computer, and the new version uses different DPI in the SVG files it saves than the older one, and than what Fritzing assumes on import. But it was consistent, so the part outlines exported from Fritzing didn't get resized, thus the holes for the switches fit fine. The whole keyboard is just larger than it was supposed to be. The angled keys only made it difficult to confirm.
I only discovered this just now, while working on the #Flatreus design. Sure enough, the same thing happened there, so I had to practically re-do all the routing. Thanks Obama.