About the French translation update from Olivier.  It has been checked into the Git repository.
@Pierre - there is a Mint18 build if you would like to check it out at:
and as usual it contains a bunch of other changes to include some masking fixes (later I will update BT #2)

2. edited po/xlat.sh and added "--from-code utf-8" to the xgettext line
The above has been corrected xlat.sh as you provided and checked into GIT just now. 

4. ran: msgmerge -U po/fr.po po/cin.po
I have updated the documentation here locally in the manual Translations chapter to recommend your method as being a lot simpler to follow.  And I will update the cinelerra-gg website also because being a lot less complicated may result in more language translations.  Thanks for all of your help.  gg/Phyllis