Each () can only capture one thing; if it's repeated, the $<digit> variable gets whatever was captured last.

Since there are only at most 4, try:

$temp_=~ /\!(\S+?)            #tablename
         \[(.*?)\]            #table variables
         (?:\[(.*?)\]
         (?:\[(.*?)\]
         (?:\[(.*?)\])?)?)?
          \s+.*/x;            #white space then rest of text.
    print Dumper ($1, $2, $3, $4, $5);
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