Hi amic,

Switching to openjdk-8 was the solution

Which java version were you using before?

If I manage to find some time, I would be interested in contributing to the french translation, which is quite cumbersome at the moments, for instance ”wiring” is translated « plantes » which has really nothing to do . Could you tell me where I could help you for that ?

Extract the plugin as if it is a ZIP archive (you can use 7zip or any other compression program. Navigate to the subfolder "it\ld\sh3dplugins\wirings\resources\", here you will find a file named "package_fr.properties", open it using a text editor, and change the text lines. You can post the file content on the plugin page on sourceforge, and I will insert it in the next release.

A strange behaviour is that when I press ESC after having drawing several points, nothing happens… So I need to manually click on the button "Draw wiring" to untoggle it, then it finishes creating the wire.

The ESC key only works if the 3D view has the focus. This would be the normal condition when working with wirings, however if you click the 2D view or the furniture catalog the 3D view will lose the focus. May be this your case?

I would want to draw wirings from the first floor to second floor for instance (and also across rooms). I did a new separate level called "wirings" to put all my wires, and I gave it a height corresponding to both floors. I am not sure I can manage to do what I wanted with this configuration. Across rooms it seems to be ok, though not responding very easily.

Having a dedicated level (or even multiple levels) for wirings is a good approach.
One limitation is that drawing on the ceilings actually uses the current level height, so if you extend the height to both floors, you won't be able to draw on the ceiling of the first floor. I'm quite sure I made it work this way because ceilings are not "pickable", but perhaps I can find a better workaround.
By the way, I need more details about what you mean with "not responding very easily".

It seems that the plugin is not very adapted for homes with intermediate floors (unfortunately, that is my case…).

As an example, if you draw a room at elevation 0, then do another level at elevation 100 with another room (not at the same location), the drawing does not respond very nicely.

That's true, linking 2 points at different levels and location doesn't work out of the box. The workaround is to set intermediate points:
1) start from the lower level, and set a point on the wall;
2) move the view point at the upper level so that you see the floor at the position where you placed the previous point (on the lower level), and place a point right there (you may check the vertical alignment looking at the 2D view;
3) place a point whenever you want on the upper level, it will work correctly on both floors and walls.