It is conceivable that they could use software to correct for this. Is there is something they can measure that indicates the amount of dilution with interstitial fluid,there might be a way to take account of it. Similarly you'd want to correct for hemolysis
I doubt that they'd be able to correct this with software. Take for example Mineral X. A concentration higher than 1mg/ml of X in blood may indicate disease D. Imagine that the tip of the finger has a much higher percentage of X than any other body parts. In testing for D you'd get a reading that may or may not be wrong as you wouldn't know if a high concentration of X is as a result of disease D or as a result of the machine's inherent error. Your screwed both ways. Theranos should understand that it isn't just a traditional software company that can release an MVP for the public. One screw up and their reputation is tarnished for ever. Just ask Volkswagen ;)