> Get a judge having a bad day in France and your case could go belly up regardless of merits, customs or precedent.
You're spreading FUD. 1) Few civil actions are decided in a day. 2) You can almost always appeal a decision. 3) Statutory law in Civil Law countries tends to be much more detailed and comprehensive (compared to statutory law in Common Law countries), precisely because no one likes to "retread the same legal wheel over and over", so law makers at some point decided to codify what already was (or was supposed to become) common practice. So judges have much less wiggle room in their decision than you and OP are implying.
This is also the reason why "commercial agreements drafted in civil law countries tend to be rather brief […] since there is no reason to restate codified law"[0].
[0]: https://www.vistra.com/de/node/905