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Jupiter conjunct South node happens about every 8 years or so.

The last time it was in libra was 1968-69 but then only at early degrees. I can't find any case of it happening around the middle libran degrees in the last 200 years. But it has happened at the middle of the other cardinals; cencer a couple of times in the last 100 years and in middle of aries back in 1810!

Unfortunately I don't know how it manifests- you could take a look at the charts of some famous people who have jupiter/south node regardless of sign and apply libran concepts to that, or look as this is a mundane question perhaps look for countries that have it in their charts.

Maybe we'll just have to wait and see!