Thanks for this great explanation ! I think your way is a better solution but I don't knew I can submit same version more than once (while not accepted), that's why I don't knew how to do.
For the moment, lot of work to split language files and make update.
Create modx fr.xml and update modx xml from RC1 to RC2.
Same problem, when it is accepted by you, I need to make it accepted by french team for the french version, What I need to do if you accept it and french team refused ? ah ah !
Make in parallel 2 (RC + stable) version will not very simple to manage with SVN...