Complex sentence: He had an engagement at the Karlsruher Hoftheatre, and his performance impressed the theatre director, Joseph von Auffenberg: in 1826 he offered Haizinger a lifelong engagement at the theatre.
Split into simpler sentences: He had an engagement at the Karlsruher Hoftheatre. His performance impressed the theatre director, Joseph von Auffenberg, and he offered Haizinger a lifelong engagement at the theatre.