Similarity plugin with French Language

I'm using the Similarity plugin with org.apache.lucene.analysis.fr.FrenchAnalyzer and I got strange results when searching close terms for a word. Some of the candidate term representations are mutilated in a strange way like: pieuvre -> pieuvr, mobile -> mobil, chouette -> chouet, pattes -> pate, mieux -> mieu and the 'central' word telephone -> telephon. similarity with the term 'téléphone':

I join the tiny rdf example:

@prefix : <http://data.edf.fr/ontologies/ideeShaker#> .
@base <http://data.edf.fr/data/ideeShaker/>
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<1> a :Idee;
  :content "Le téléphone à pieuvre n’est pas mobile.";
  rdfs:label "Test1" .

<2> a :Idee;
  :content "Un tien vaut mieux que 2 téléphones";
  rdfs:label "Test2" .

<3> a :Idee;
  :content "La pieuvre a huit pattes";
  rdfs:label "Test3" .

<4> a :Idee;
  :content "La pieuvre et mobile Dick";
  rdfs:label "Test4" .

<5> a :Idee;
  :content "Pieuvre possède un portable";
  rdfs:label "Test5" .

<6> a :Idee;
  :content "Le téléphone à pieuvre c’est nul";
  rdfs:label "Test6" .

<7> a :Idee;
  :content "Le téléphone mobile c’est chouette";
  rdfs:label "Test7" .

<8> a :Idee;
  :content "Une pieuvre est mobile";
  rdfs:label "Test8" .

<9> a :Idee;
  :content "Une pieuvre et un téléphone";
  rdfs:label "Test9" .

<10> a :Idee;
  :content "Telephone à la pieuvre";
  rdfs:label "Test10" .

Do you think this problem is related to the Lucene analyzer ot to the GraphDB integration?