White Cream is a compound stain; other than the Zinc Oxide, the other protein component may coagulate into the protein leather fibers that will cause stiffness to the tactile-feel; and that oil and fat component may have a darkening effect to the appearance.
A holistic leather-safe approach I would practice will be first use a pH 11.0 leather protein remover to remove the protein component; follows with a pH 2.2 leather degreaser that will remove the penetrated fats and oils and at the same time neutralize the high alkaline pH and rinse off with a pH 3.0 leather rinse.
When the stain is gone you may recommend a non-stick protection that imparts a classic leather scent; this protection will make future cleaning easier and still retain the breathability for seating comfort.
Perhaps this Problem Solving Guide may gives you extra confident when comes to cleaning and conditioning suede.
Roger Koh
info@leatherdoctor.org