I did some more tests today, here is a summary:
If I convert the fp7 file using FileMaker 12v1, everything work fine.
If I convert the fp7 file using FileMaker 12v2, I have to rename some fields if I want it to work. The errors occur when trying to create some related records using the "setField" command. As I said it look like the error is triggered if a word in a field's name start with an accented caracter.
The 4 fields I had to rename were:
php_Panier et Archives::Mot de passe Étudiant Chaque Fiche
php_Panier et Archives::État
php_Panier et Archives::Retouche associer à cette facture
php_Panier et Archives::Prix Téléchargement Étudiant
I had to rename them like so to make it work:
php_Panier et Archives::Mot de passe Etudiant Chaque Fiche
php_Panier et Archives::Etat
php_Panier et Archives::Retouche associer a cette facture
php_Panier et Archives::Prix Téléchargement Etudiant
But I don't get the error when displaying the content of the field using the "getField" command, even if a word in the field's name start with an accented caracter.
I also tried the "New FileMaker 12 Standalone Converter", but get pretty much the same result as when converting with FileMaker 12v2, except that now the database is 2,39 Go instead of 1,94 Go, the original fp7 file is 1,95 Go.
It worry me that i get the best result with the v1 and that in the "New FileMaker 12 Standalone Converter" documentation, it's say that if you don't use the converter, to use a minimum of FileMaker 12v2 (due to an issue involving certain Unicode characters [but to me, it look like there are still some issue there, at least with the cwp]).
So I guess my best bet is to convert with 12v2, rename some fields, do a lot of time consuming tests and hope that next update don't bring more troubles...