Yes. If it is already a symbol in the drawing, go to Symbols -> Symbol Manager, select the symbols from the list, and use the save as catalog to create a new catalog with the symbols.

If it isn't already a symbol, but just loose entities, you can define them as a symbol first using Symbols -> Define Symbol, and then you can export it to a symbol catalog file as described above.

To add it to an existing catalog, do as above, then open up the existing catalog for editing by opening it up using file -> open as opposed to just open it in the symbol catalog window, then go to Symbols -> Symbol Manager, hit Import, and pick the catalog file you created above.

Did you try inserting into a new map in a completely different style? Still trying to figure out if this is something spesific to that Cosmographer template, or if it a general problem for you.

Oh, and since nobody remembered to ask this yet as far as I can see, you have installed the latest CC3+ update, right (3.98)?

Are you putting the image on it's own sheet? Not that this is required, but it makes it easier to handle to avoid for example the image ending up behind the background or similar.

When you insert the image, do you properly give it two corners as the command line asks for. The two points you provide as corners determines the size of the inserted images, so if you click two points really close to each other when inserting, it will be tiny.

Also make sure the image is actually a png image. Try to open it in a local image editor or something. Lots of websites does weird things, so you may have accidentally ended up with the html code for the page saved with a .png extension instead of an image.

That's a consequence of using the drawing tools from the "wrong" style. Did you start this as a Mike Schley overland map in the first place?

See this FAQ entry for how to import the missing fills.

Are you talking about the Mountain Range tool or the Mountain Fill tool here? One is based on symbols, the other on a bitmap fill, so the procedure will be a bit different.

For symbol based tools, they adhere to the default symbol size you can get at by hitting the :CC2PRESETS: button. This must be done before using the tool.

For fill based tools, you need to change the scaling for that particular fill. You do that by clicking the fill style indicator on the status bar, going to the bitmap files tab, find the fill in the list, and then change the values for scaled. This can be done before or after drawing with the tool.