OK - here is updated code - one line added, and some tweaking to count parens, but still using the flip-flop. This works with your variation of the data...

I'm nor arguing your point that my original code was a hack - I simply wanted to illustrate the value of the flip-flop operator for this type of situation, including the fact that it CAN be use properly in production level code, and that it simplifies code.

##! perl -slw
use strict;
my $p=0; # Counts number of unmatched parens
while( <DATA> ) {
   ##m/\(TIMINGCHECK/ .. do {$p++ for m/\(/g; $p-- for m/\)/g;$p==0} o
+r print , next;
   ## Faster+simpler version, plagerizing BrowserUK's paren counting m
+echanism
     m/\(TIMINGCHECK/ .. ($p+=tr[(][(] - tr[)][)])==0 or print ,next;
   print "//$_"
}

__DATA__
(CELL
  ...
  (TIMINGCHECK
    ....
    ....
  )
)
(CELL
 (CELLTYPE "SEDFQD1")
 (INSTANCE uTrigger/TrcInclCtrlReg_reg[13])
 (DELAY
 (ABSOLUTE
  (IOPATH CP Q (0.10:0.15:0.25)(0.09:0.15:0.24))
 )
 )
 (TIMINGCHECK
   (OTHERTEST
  (SETUP (posedge SI) (posedge CP) (0.14:0.23:0.41))
  (SETUP (negedge SI) (posedge CP) (0.09:0.16:0.30))
  ....(random lines)
  (HOLD (negedge SI) (posedge CP) (0.00:0.00:0.00))
  (HOLD (negedge D) (posedge CP) (0.00:0.00:0.00))
 )
 )
)
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