two general comments: use code comments, e.g. || /foo\d+/ #match foo1234 and also look at the /x modifier in perlre for embedding whitespace and comments inside the regex itself.
Also, the parens are unnecessary in (/foo/) and (19\d{2}).
Here's a (untested) crack at it (also restructing into one RE, since there are commonalities):

if(
  /(   # start re & capture
    (?:  # non-capturing OR clause for the following cases:
      \d{1,2}\-\d{1,2}\s\w+      # "03-25 X"
      |
      \d{1,2}\w{2}\s\w+          # "03aa X"
      |
      \d{1,2}\s\w+               # "12 X"
      |
      \w+\s\d{1,2},              # "X 12,"
      |
      \w+\s\d{1,2}\-\d{1,2},     # "X 12-20,"
    )
    \s19\d{2} # the <spaceChar>19xx marker
  )/gxi
){
  ...
}
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