-w will help you understand what's going on.

$ perl -we "print (localtime(time))[2]"
print (...) interpreted as function at -e line 1.
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.
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use diagnostics is even better.

$ perl -Mdiagnostics -we "print (localtime(time))[2]"
print (...) interpreted as function at -e line 1 (#1)
    (W syntax) You've run afoul of the rule that says that any list op
+erator
    followed by parentheses turns into a function, with all the list
    operators arguments found inside the parentheses.  See
    perlop/Terms and List Operators (Leftward).
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So stop the parentheses looking like a function.

$ perl -e "print +(localtime(time))[2]"
16
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