The main problem is the second pictures where the finish is wear off.
This looks like a three layers finishes, a primary white color that blocks off the grayish blue leather crust, a secondary ochre color that is again over colored with a tertiary brown color to produce a simulated aniline leather effect. A complete restoration has to be in the sequence of the coloring order.
Prior to a color refinishing the stain areas is probably be degreased using a waterbased Degreaser-2.2 (pH 2.2) follows with a pH stabilizer using Acidifier-2.0 (pH 2.0) prior to a color refinishing system.
In this wet preparatory cleaning, the first picture surface residue will be stripped off as well.
This is a refinishing work rather than cleaning to improve the appearance and restore the leather pH integrity.
Cleaning just remove the surface residues, is that what you would like to do?
Does the stain area feels sticky when feel with touch?
Let me know you decision and I will recommend accordingly.
Roger Koh
[email protected]