Hello
The solution is :
- when you do a symbology by unique values in the properties of the shapefile in the table of content, you cut all text in the column of "label" after clicking on "add all values". Then, for each line of symbology, you create a "description" where you will paste the text you have cut. The first line in the first language and the second line in the second language. In the descritption window, if you want to go on the next line, it is Ctrl+Enter
- after creating your descritption, create normaly your legend. In the properties of the legend, go to "items", then on double click on the name of the shapefile you are working on, and then be check "show descriptions".....OK..... OK
This last step will make your description seems to be labels just next symbol, but in 2 lines.