Suggesting similar:

For variable $s with string text ...

tokenize($s, '/')[position() = (last()-2 to last())]!replace(.,
'.*\}(.*)\[.*', '$1')=>string-join('/')

Looks way better, I always feel I shoot myself into the foot if I need
to mix ! and => and need a lot of parenthesis but your attempt seemed to
elegantly avoid that problem.