Did you test it on this page
http://tiddlywiki.com/languages/fr-FR/index.html ?
Because I can reproduce it (on Chrome for example). If I dowload a copy, there is indeed the same bug.
I always start with a empty file, which is OK. I read on other groups that you start to contribute on translation, that maybe why you want to work with this file.
So, I don't have any idea why it is broken. Xavier ? Any idea ? A wrong pullrequest with syntaxt error on js content ?
Best regards,
Sylvain