His teaching duties at the PTM Conservatoire, his journalistic and editorial work, as well his involvement in Lwów’s social and cultural life, meant that Koffler could only compose music in rare moments of leisure, especially during the summer holidays. By 1939 his catalogue comprised 24 opus numbers, apart from some pieces of a lower calibre (including functional and occasional music) that were not officially listed.
By the time of his death, at least five more items were added to his oeuvre. A large proportion of Koffler’s works from all periods must now be considered lost (according to the present state of research). Lost compositions include Divertimento (Little Serenade) for reed trio, Piano Sonata, and Polish Suite for orchestra. Early pieces (up to Op. 5) are known to have been destroyed by the composer himself. Only Zwei Lieder, Op. 1 survive from that time. There are also some dubious cases and items only known from mentions in the press. A separate category of works for children can be distinguished (comprising Little Pieces for Children, originally as Op. 16a, and the Kyiv print of Chotyry dytyachi p’esy [Чотири дитячі п'єси] for piano).