The way you worded your question makes me wonder if you are counting the whole amount of cream as fat in your recipe. If so, that might give you some trouble. ???
Yes, I have used cow's cream and coconut milk in a few of my soap recipes. The total cream in one recipe was 393 g. Of that, 45 grams was butterfat and the remainder (the whey) I counted as water. The butterfat was 3% of the fats in my recipe.
It's certainly something to try, just to say I did it, but I don't feel the added butterfat gives my soap any unusual benefits.
I have used straight butter in soap to provide about 17% of the total fat. It worked fine, although the butyric acid in butterfat adds an unusual (some say bad!) odor to the soap. As with cream, the butter was fun to try once but is not an ingredient I feel adds a lot of benefits to a soap.