If your serving pressure is within usual beer ranges then the line length is not the problem here.
Unless the line diameter were mis-marked, I'd be looking at the variables of temperature or the agitation introduced by your 1/2"TC and reducer. If you're confident there are no temperature changes across the line (e.g. if the tap or line are warmer) then maybe try switching out the 1/2"TC with a 1/4" outlet.
You could give this a go but I would be a surprised if this made a significant difference.
How big is the tank that you are connecting to? What is the difference in height from the tap to the top surface of the liquid?