Tanks Gato for this advise
I have dowloaded notepad2, and created a very simple text fashcards list, making 4 copies or it, one in each encoding format available on notepad2: Unicode / Unicode Big Edian / UTF-8 / UTF 8 with signature.
As my Palm Z22 has no card, I then have to convert these txt files into PDB file, using Wave PDB
Then I import these 4 lists from the flashcard import menue of Pleco (using either encoding UTF 8 or GB 2312)
Nothing works (le list created has one entry, with a wrong character)
However, because I managed to import a PDB HSK list available on Pleco website, I believe that the problem comes from Wave PDB. Any alternative ?