There is no way of specifying the layer within a symbol catalogue.

Layer specification occurs at a later stage when you create a new catalogue setting and filter for the catalogue when attaching it to a button. This process is explained on page 103 of the Tome of Ultimate Mapping, or in this blog by Remy Monsen (which also includes a link to a section of a live mapping session he did that may be more useful than trying to read reams of text in English).

Layers cannot be set for individual symbols, but they can be set for the entire catalogue. That is why the symbols of most styles are carefully separated into catalogues that reflect their type and the layer they should end up on, such as Structures.FSC, Vegetation.FSC, Traps.FSC, etc.

Whatever translator you are using is working very well - better than Google Translate... unless they've massively improved Google Translate since I last attempted to read an article in a language foreign to me :)

...

This is just a personal observation here, but you do seem to be placing a huge emphasis on the importance of layers. They really aren't that important, as can be seen from the way there are generally fewer controls and settings for them wherever you look. Far more important are the sheets and effects.

Unless you have specific reasons for wanting a symbol to be predefined in the template itself, it's better to have an empty Symbols in Map pane when you do the final save on your template.

Examples of symbols left in the template at the final stage can be examined in any style you are using by checking what's already there when you start a new map and before you do anything else. I believe some of the overland styles have things like compasses, titles, and scale bars predefined that way.

This way, the symbols you then paste from your carefully crafted catalogues will behave exactly as expected.

If the symbol already exists in the template prior to the modifications, and has been there throughout (check Symbols in Map by clicking the left button above the symbol pane), the symbol will behave the same way it always used to with respect to which sheet it goes on.

To make it behave you first need to delete them all from the template by deleting them from the Symbol Manager, get the catalogue you just saved open in the symbols pane, and try again.

I'm not able to explain it either, but I created a new sheet called "Backing sheet" and copied the polygon from TERRAIN MOUNTAINS 2 onto it with no sheet effects. It seems to be ok now. Let me know if it stops working, or doesn't work as well as I first thought.

There are a lot of nodes on the end of your crosshairs, and if your coastline is more intricate than the one Ralf was using as an example in that video it will behave as you describe until it is pasted.

Perhaps an easier thing to do, rather than trying to move all those nodes around until you can get the cursor to the corner, is to type the paste origin in on your keyboard and hit return. That's 0,0 (zero comma zero).

Then right click to clear the crosshairs before you accidentally paste it a second time.