$5 = '(if (string-match org-timer-re $3) (org-timer-secs-to-hms (- (org-timer-hms-to-secs $2) (org-timer-hms-to-secs $4))) "")
becomes: $5='(if (string-match org-timer-re $3) (with-time t (- $2 $4)) "")
$5 = '(if (string-match org-timer-re $3) (org-timer-secs-to-hms (- (org-timer-hms-to-secs $2) (org-timer-hms-to-secs $4))) "")
becomes: $5='(if (string-match org-timer-re $3) (with-time t (- $2 $4)) "")