I don't have much more on Ludwig Falck.
The full citations for the two Ludwig Falck Church records are:
St. Michaelis and Zion Records (Pennsylvania German Church Records, Vol. I, pg. 599)
Falk, Johann Ludewig,
Schulerin, Anna Christina; m. December 24 
Witness: Daniel Eder, Johannes Berg, Friedrich Maut [sic - Maus], Jurg Kurtz
St. Michaelis and Zion Records (Pennsylvania German Church Records, Vol. I, pg. 538)
Ronau, Susannah Margretha, dr. Peter Ronau and w. Cathrina Margretha (newcomers)
b. Aug. 30; bap. Sept 23 
sp. Ludwig Falck, Susanna Margretha Mausin [Susanna Margretha was the wife of Frederick]
There are several additional records for the family of Frederick Maus (he remained in Philadelphia).
Annette K. Burgert indicates that Samuel Maus (of unknown relationship to Frederick) was married to an Elizabeth Schuler. Both Maus men (as well as George Mouse who was killed at Seybert's fort) had roots in Hornback as well as being mentioned in the records of St. Michaelis and Zion Lutheran Church in PA.
A working hypothesis for Ludwig Falck is:
Arrived in Philadelphia on the Sally in Oct. 1750. (This may have been a vessel in which illness wiped out a large number of passengers so keep open the possibility that Ludwig may have lost a wife on the trip.
Ludewig Falk married Anna Christina Schuler 24 Dec 1750 in Philadelphia. (Witnesses include Friedrich Maus who was the brother of George Mouse who would be killed in April 1758).
Lodwowick Folk appears on a list in Hening's Statutes for re-imbursement for supplies to the militia during the French and Indian war.
Loudwig Folk appears on a list in Hening's Statutes for re-imbursement for what seems to have been militia duty under Capt. Abraham Smith (whose bailiwick included the South Branch). The names nearest him were associated with the Upper Tract area.
It's likely Falck arrived on the South Branch between 1753 and 1757 - and, of course, he was killed at the end of April, 1758. It's possible he's mentioned in some of the probate material which Eric Hedrick has recently digitized but I haven't looked for him specifically.
(I inadvertently typed 1758 - rather than 1750 - for the arrival of the Sally and have corrected in this posting.)