If you guess at random, that's 25% probability to get the right answers, which gets you 7/28 points in average. I got 14/28 by trying hard and I still hate the result, but it's also true that the questions were largely impractical: noone parses dates like this in a real production app. We always validate the date format first. So noone should feel bad at their results.
Anyway, after the experience trying to automate something with Google Sheets and wasting 4 hours just to discover that months start at 0 (in the context of parsing string dates and creating Date objects)... yep, no more JS for me.
I think my strategy for JavaScript going forward is to 'drop & run'.