One way you could approach it is to decide the size of the average house. A medieval or earlier house for commoners were usually a tiny affair, often no bigger than my living room. Then, based on your house size, so you can used that against the sketch to determine size.

Change the display quality using :CC2RESMODE:. Set it to Fixed - High or very high. After doing that, you can try setting it back to automatic and clearing the bitmap cache, but if the issue remains, just leave it at fixed.

CC3+ uses 4 different resolutions for performance reasons, and what you see here is one of the lower texture resolutions being displayed instead of the higher one that probably should have been displayed in that situation.

Note that "Sample size" is just the size of the sample window, it doesn't affect the drawing.

File -> Save as, then pick an image type such as .jpg. You'll probably want to hit the options button in the dialog AFTER picking the file type to set up the resolution you need.

This is a lesser-seen case of the 'Transparency Acne' effect. CC3+ calculates edges by looking for differences in colors.

What happens here is that the lines doesn't go on top of the text, but because the text appears on top of the halftone lines, CC3+ sees differences where the fill has white pixels, and unchanges where they are black. This causes the glow on the text to behave as if the text was full of little holes, and fills those holes with the white glow.

The best way of handling that is to change the colors on your underground railroads from black to a dark grey, just pick the darkest one. Since it isn't black, CC3+ will see that as a difference, and you are fine.

Did you try Shessar's workaround above?