Since no one else answered, I'll turn my comment into an answer. Note that I'm not an expert on cat nutrition, and all my knowledge comes from 'random' pages I googled.
The amount of salt in Kiri cream cheese can be found here. A serving of 18 g contains 95 mg salt (sodium), or roughly 0.5%. The average adult cat only needs very little salt, some say 20 mg, some say 42 mg. So 4–8 grams of Kiri (less than a teaspoon) would contain the entire daily salt requirement for a cat.
Note that proper pet food, at least the high-end brands, should already contain everything a cat needs.
Regarding lactose, I couldn't find anything about this specific brand, but cream cheese in general contains ~2.5% lactose, so the previous owner's claims doesn't seem to be true. As already mentioned by @Kai , hard cheeses contains less lactose than soft cheeses, as can also be seen here.
One other thing, Kiri contains pasteurized milk, which cats also shouldn't have (source 1, source 2).
So, to answer your question: No, Kiri does not seem to be safe for cats, at least not in high quantities. I suppose that the occasional lick of cheese won't hurt, but you should probably keep it to a minimum.