In import log I see that your operating system is Windows since server is using WE8MSWIN1252 character set. Only NCHAR column datatype will use Unicode character set so are you getting converted characters in columns with NCHAR (or NVARCHAR etc.) data type?
Then you are pretty much stuck I think. If not, I would do import with chacater set which your server is using i.e. WE8MSWIN1252 and set language both in the register and on the session level before import starts:
in the Registery NLS_LANG=American_America.WE8MSWIN1252 and in DOS set NLS_LANG=American_America.WE8MSWIN1252.
Alla S. Pfauntsch
"Life is what happens while you are planning something else".