Thanks for these suggestions. I have pored through box after box after box of materials at the Moravian Archives in Bethlehem, looking for traces of Albrecht while he was in Bethlehem, Christian's Spring, and Lititz, and have found some interesting things, but I am sure there is more to be found in places I haven't thought to look.
It hadn't occurred to me to consult Moravian records related to his time in Germany. One problem with any such search, though, is that Albrecht's time in Herrnhaag coincided with what later Moravian historians refer to as the "Sifting Time," a moment of extremely radical religious and social experimentation--so extreme that by the 1750s the Moravian church was so embarrassed by it that it began to systematically destroy materials related to the period. As a result, both the congregational and the single brothers’ diaries of Herrnhaag for the years 1748 and 1749 (when Albrecht was there) were destroyed. It may be that other materials from Herrnhaag during these years were not destroyed, and I'll check on this.
Scott