my @lines = split "\n", $schema;
for (@lines) {
  ...
  s/\)\n/\);\n/;  
  ...
  }
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None of the substrings split from  $schema in the
    my @lines = split "\n", $schema;
statement will contain a newline because you're splitting on a newline, thus the match regex of  s/\)\n/\);\n/; will never match.

To add a ';' (semicolon) after a ')' (right-paren) that was at the end of a newline-terminated line, try
    s{ \) \z }{);}xms;
or maybe to be on the safe side
    s{ \) \s* \z }{);}xms;
(I assume you're stitching all the lines back together with something like a
    $schema2 = join "\n", @lines;
statement).