Vintage Veg dyed calfskin

[Armagnac]

I recently acquired a set of 3 Italian suitcases made by Prada from the early 1970s.   Structurally they’re in great shape and their surprise Polo green interior is in excellent condition, however there is quite a bit of black marks and spots.   From what I understand these are Saffiano leather, developed by Prada, it’s heat stamped down and then a coating is put on it to make  it very  durable.    I’ve had very little luck using a PH balanced mild cleaner like Howard.   Not sure what my expectations should be.   Lots of contradictory advice online on whether you can use a conditioner or color balm.    I’d like to restore them to the best possible they can look.   How do I restore these? 
 

https://imgur.com/a/Wa8WsSj

[Armagnac]

I recently acquired a set of 1970s Italian suitcases made from veg dyed calfskin, I believe they were stored in a garage a they have a lot of black marks throughout.   What can I do to mitigate this , what’s the best to hope for ? The interior is a great Polo green Saffiano leather and are in excellent condition.