Complex sentence: Kate has known about Katya since the time Geoff and Kate met later in the 1960s, is initially unconcerned by Geoff's controlled disquiet and helps him find his old German-English dictionary the next day.
Split into simpler sentences: Kate has known about Katya since the time Geoff and Kate met later in the 1960s and is initially unconcerned by Geoff's controlled disquiet. She helps him find his old German-English dictionary the next day.