Good hint, but there is neither 'Forest Spirit' nor 'Iron Arnie' nor 'Mars' etc. to find.
When you search for names like 'Forest Spirit' or 'Iron Arnie' one can see that these names occur only in files in directory G:\Games\World_of_Tanks_EU\res\text\lc_messages
But these files are in binary format as in 'usa_vehicles.mo' and 'ussr_vehicles.mo', so apparently hard coded or am I wrong?