That (the German origin) is an intriguing thought, one which you and I may have discussed in earlier correspondence, based in part on a few entries in German church records in Frederick involving Alexander Beall. To avoid confusion on the part of anyone else reading this reply, Jack and I are not referring to any of the Scots named Alexander Beall in Prince Georges, Frederick and Montgomery Counties, Maryland, but rather to Alexander Beall the son and heir of William Beall who secured a warrant for a survey of "Long Lookt For" in the Benett's Creek area of southeastern Frederick County (as I recall) about 1754. Alexander and his apparent brother John Beall also lived at times just over the county line in or near Browningsville in the adjacent northern section of Montgomery County.
The DNA information that someone sent me (unfortunately I don't remember who) indicated that the Browningsville Bealls' descendants Y-DNA data matched that most commonly found in Northumberland and Cumbria. Historically that area was overrun from time to time by Celts, Romans, Angles, Saxons and Vikings, so the ultimate source of this brand of Beall DNA could easily be Germanic. In terms of 17th century sources, I don't find anything very promising in the Philadelphia passenger lists / oaths of allegiance. Two men with the Biehl surname and one named "Bielle" arrived in Philadelphia Oct. 1 1754 on the "Phoenix," but their given names were Peter, Daniel and Johans; not Wilhelm. Six years earlier, Michel Bihl had come on the "Patience & Margaret." On the Anglicized list of names, his appears as "Michael Bayle," age 28. Again, no Wilhelm / William. A Peter "Bale" is on the 1790 census of Ralph Crabb's first district of Frederick County (apparently the area between Woodsboro and Urbana). A William "Bail" is found at page 264, in a heavily German area of the County. I have some other random notes on Peter Biell / Bayle / Beal; not so much on William Bail. However, I have found nothing to convince me that they were related to William Beall of "Long Lookt For."