NFS share from Linux with accented and non-ascii characters - files work in terminal but not programs
OK - I found here https://discussions.apple.com/message/21199204#message21199204 the answer. I quote:


  After much reading I learn't there are multiple ways to construct the
  same unicode character, and so for efficient comparision there is a
  concept called normalisation ( http://www.unicode.org/reports/tr15/ ).
  After normalising with the same algorithm the representiation of any
  character will be consistent.
  
  Sadly there are multiple normalisation algorithms and no concensus on
  which to use. Apple use NFD, where as most other operating systems use
  NFC. NFS does not specify a normalisation method, so OSX cannot
  confidently convert out of the box.
  
  All I needed to do to fix this was to tell NFS that my NFS shares used
  NFC. Then all the files with the odd characters appeared and read
  fine.
  
  I did this by adding this line to /etc/nfs.conf on the Mac.
  
  nfs.client.mount.options = intr,locallocks,nfc


Works perfectly.



Addition: 
The options intr,locallocks are not related to character encoding so the solution should be workinf=g without these, i.e.

nfs.client.mount.options = nfc


Although I haven't tried this as these two options make sense in my usage scenario.