Copy/paste lang incompatible content works but creates "fantom" content items: should we prevent such copy or ask to change lang on the fly

Cf: general parent ticket for general use case.

You can copy a content in one/several lang and past it into a site with incompliant lang (e.g: ACME in FR/EN to a DE-only site).

#1: If you past it directly on a non-activated area, nothing visual happens but this still create an "orphean" content item in the Site/Content Explorer.

#2: If you past it on an activated area, this only mention the list with a "Add to how-to-use-this-demonstration:" and the attached big_text is only available in the content explorer.

In case:
#1: Should'nt we prevent pasting objects in non activated areas? Or automatically turn-on the area in such a case?
#2: Shouldn't we detect the incompatibility of lang and ask if the user wants to reuse the content available in one lang from the source in another lang in the destination? This might become quite complex when you have several compliant/non compliant lang (e.g: Site A: DE/FR/IT and site B: FR/ES/NL -> UI required to map incompatible lang to others?).

Or should we at least warn the user with a small warning that he is copying items which do not exist in the current site?