I did what I could with a Google search to research Johann Jakob Gottfried Biller (or Bühler), and I'm somewhat uncertain. The maker's mark on these spoons is actually spelled "Bihler," although I don't know how clear that is in the photos. Is this a known mark for Biller?
There's another site called Hallmarks Encyclopedia that lists the date for the "L" Augsburg mark as 1753-1755, which is earlier than the dates you mentioned, but I was not able to find much more info on Biller, besides a few pieces listed at auction houses (which didn't show the marks clearly in the listings).
I also found reference to an A. Lorenz Bihler (with that spelling) listed as a goldsmith in Augsburg circa 1730-1740. So now I'm thinking maybe these different people with similar names and different spellings were relatives?
Along with these spoons came some knives that have the same Augsburg "L" mark, and apparently have hollow silver handles with steel blades. The knives have a different maker's mark, though: WHI inside a trefoil. They also have a mark of FCB on the blade, which I think was a monogram, that appears to have once been filled with gold colored inlay.
Do you recognize the WHI mark?
Sorry for asking so many questions. I know almost nothing much about German silver marks. I just recently found this lot of very old flatware at a local estate auction, and since there was one spoon marked 800 with a crown and crescent, I did some research, realized that several pieces were probably at least 800 silver (some were also marked 13 Loth), and purchased the lot. It was the City Marks database here that made me think maybe these few knives and spoons were from Augsburg.