You have the correct answers already. However, I thought it worth mentioning that the line in question can be made potentially less confusing by discarding the unwanted elements of the list on the left side of the assignment rather than the right. That is you can replace

$bcsdir = (<${bcsdir}*>)[0];
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with

($bcsdir) = <${bcsdir}*>;
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The brackets on the left enforce list context and with only one element inside those brackets all bar the first result are discarded. The braces are not needed either, so it can be slimmed down further to just

($bcsdir) = <$bcsdir*>;
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Which of these is actually clearest is likely in the eye of the beholder.