You have J. Erhart about right. My notes on him are from circa 1866-1899. The Kaiser first used his gun in 1870. I wouldn't know about his association with Lechner. He was listed as a merchant in Graz and probably partner in Lechner & Jungl there. They started traded in firearms in the middle 1870s.
I do not know anything on Templer.
Schaschl was a well known family of gunmakers but I don't know about any specific markings. Similar on Umfahrer (who went out of business during 1870s).

With kind regards,