I wouldn't worry about it, the spring does nothing once bolt is tightened down. If tension falls off no real biggie anyway. The later stuff nowadays (zetec) uses so little tension most people have a tendency to overtighten them. It often fails the belt since belt has no real guides, tightening it then makes the belt steer to pulley edge where it frays and DNF.
The spring is actually only correct with a NEW belt, once belt is run in then the spring is actually too much. Meaning you should not back off the tensioner unless changing the belt. Backing off to retension later in belt life shortens it, the tension is SUPPOSED to drop off as engine runs, the lower tension later allows belt to last longer.