This is a very easy and short tutorial. If you have a unit added in and you see in custom battle it doesnt have a name and says "unlocalized placement text" just do this:
1) Go to text folder(considering you have converted the files in it) and go to export_units.
2) Add your new unit there in brackets like
{bagaturs}
make sure its perfect in the brackets with right capital letters and perfect spelling then create another after
{bagaturs_descr}
there add the long description you will see on the unit scroll
and the last to add is
{bagaturs_descr_short}
this is the short description you will see in custom battle if you put the cursor on the unit.
Simple and easy