Sorry I can’t translate my answer to spanish personally, but I believe I have an answer for you.
What I think is happening is that the SVG being created is using small segments with overlapping points to show as a complete shape. Combining them is very simple with Inkscape.
Here I have three different lines that are drawn as a closed shape but not actually connected. They only share end points.
To combine them, select all of them by pressing ‘Ctrl+A’, then enter the point editing mode, and press ‘Ctrl+A’ again to select all the points (they will all turn a dark color):
Now press the little button that looks like two-points merging into one. This will take all the points that are within a very small distance of each other and combine them into a single point.
You now have those three disconnected lines into a single closed shape. Now when this shape is imported into Easel, you can cut outside the line or inside the line, where as before it would have told you that it’s not a closed shape.