For my tuppence worth, I am not familiar with Prochems leather cleaner.
What first must be ascertained though, before any cleaning agent is applied, is to identify the TYPE of leather, as explained above.
Will the Prochem cleaner harm a nubuck leather??
Is it only suitable for Pigmented or Aniline??
REAL leather, can be any of several different types of leather.
Experimenting without knowing what you are dealing with, is hazardous, to say the least.
good luck,
Shorty.