Job application language and explaining career break?

Job advert (in German) wants good active knowledge of two out of French, Italian and German plus English. Also says they're under-represented in French and Italian speakers. Which language would you advise to apply in? My German is better than my French, which is passable.

Secondly, what is the usual way to explain away a "career break" or two i.e. children, these days? Is "Elternzeit" in the timeline sufficient? Civil service if it makes a difference. There seems to be lots of conflicting info online, so I'd be grateful if anyone has any recent experience here.

Finally, if they're offering job sharing / part time at any percentage is it better to mention in the cover letter which percentage you'd be interested in?

As a rule, always apply in the language of the advert. German here. But mention every other language you speak.

With regards to the children just write "taking care of two children fulltime" in German (i.e. Vollzeit Mutter von zwei Kindern Alter x und y).

With regards to parttime work I would state your prefered percentage and also if your open to other options i.e. more or less.

Good luck with the application