Is the polarity of diodes D1, D2 correct in Bike-TSL-Kit_RevA.sch?
Yes, checked it today it is proper, LM339 is open collector. Just put the long pin of the diode into the circle pad, as explained in the soldering guide:
https://github.com/OLIMEX/Bike-TSL-Kit/blob/master/DOCUMENTATION/bike-tsl-kit-manual-en.pdf