I haven't done a lot of printing to true scale like this. However, when doing test prints of any map, I simply save it as a rectangular section .JPG, then transfer that image to MS Publisher (albeit not for much longer, as MS is to withdraw support and cease the program shortly...), because there, I can set the image up exactly where I want it, at exactly the size I need, on whatever paper size I want. That can then be printed directly, or printed to a PDF, or saved whatever other way seems best.

The main reason I do this is because I've had horrendous problems trying to print directly from CC3 and CC3+ in the past, with fills printing weirdly, or with odd colours, etc.

If you want to try this, save the entire map as a .JPG at the exact size you need the full map to be when printed out, and leave the cutting-up into pages till you have it in a program where you can do that more easily - or the GM can, if that may be better (in case their printer doesn't like the PDFs you've prepared). As Don said, bleeping printers!

GW are not noted for their generous licensing terms; very much the reverse, in fact, judging by conversations I've had with owners of small businesses interested in trying to sell their physical products over the years, and they insist on a huge amount of control over exactly what can be sold, how much stock the business HAS to take per month (regardless of what the business itself knows will actually sell), and how it can be displayed. I can't imagine they'd be any more willing to consider something like this. If they were interested, I'd expect they'd be doing it in-house already.

It shouldn't create a misalignment if you use the snap grid properly, but you may need to mask the second grid in places. Or you could just draw one grid across all, and mask those areas of the grid that lie beyond the structure's walls.

As with most things in CC3+, there isn't just one option for solving issues like this - it's which one you're more comfortable with that typically wins the day.

If you're finding the mapping a drag, and not really enjoying it, it may be worth considering a broader-brush approach to the city overall - such as the Watabou style, that shows general areas only, with just a few important places highlighted, roads and general layout. Then if you feel so inclined, you could add detailed areas for selected spots as separate maps - that way, you don't need to worry about how the map looks zoomed out, and can pick area sizes to better suit the time and energy you have available for detailed mapping.

As Sue said, what you've shown here looks good in detail, but if it's not inspiring you, it may be worth a rethink, if only for next time.

Well, I'm at the stage now where I'll probably just get to be usefully familiar with about 25% of CC3+, and then they'll move us all to CC4 😎!