Are you selecting the lines correctly? I just did a quick and dirty import following the steps in the guide, and I had no problems trimming the entities.

However, what can be confusing when doing this is:

• The Rivers/Roads when exported from the Watabou site actually consists of multiple lines on top of each other. CC3+'s trim tools work on one line at a time, and even if that line has already been trimmed, it is still a valid line so you can end up basically trimming the same line multiple times, which doesn't really give you any progress.
• Remember that thick lines are still selected by their centerline (this is where the actual line is), not by the edge as a polygon would be

The tutorial in the Tome expects you to draw it as the image, which do have a gap on the east side (It's not visible there, but there are more islands to the east, which is why the water is less deep there).

If you need it to go all the way around without a gap, you'll have to use a multipoly to achieve that.

The tutorial files for the tome should be installed to your CC3+ data directory (You chose the location of this during the install, default is c:\programdata\ProFantasy\CC3Plus), referred to as @ in the documentation and CC3+ itself. Look for the subdirectory called tutorials located here.

So, I put together a video showing how I prepare atlas maps and discuss some of my tools. It is a bit on the longish side, but I suppose it could be interesting for some.

The sound is not perfect unfortunately, something up with my mic config. I'll get that sorted for my next video, but it is still fully watchable.

Note that the reason Sue's map was wrongly scaled here was that she though the city was in metric scale, which is quite understandable because it is actually started on a metric template, but the sizes of all buildings and symbols used are in imperial, something I hadn't noticed before the contest.

Maps are now in the atlas. Thanks for the submission.