I also have a potted Vainiglia Sanguigno tree and got some fruits two years ago. My fruits were ripe in autumn (~ October) what is pretty good in my climate where November can bring winter temperatures below freezing. The taste of my fruits was not that bad. They did not have the rich taste of, say, a navel orange but orange taste and as much acid as a normal orange. I suppose they were not totally ripe when I harvested them although they were yellow.
Regarding the inheritance of acidity, I have found an article from Cameron et. al. that states that acidless oranges crossed with normal sweet citrus produces normal sweet citrus. That means low acidity is a recessive trait in that combination. It can though happen according to the article that it is sometimes inherited in an intermediary way. In contrast, low acidity of Pumelos is always an intermediary trait in crosses with normal sweet Citruses. So the article. What it does not state is what happens when you cross acidless varieties with sour Citrus. (I read the whole article but could not find the link again. Sorry.)
I have tried to do the latter thing: I pollinated Vainiglia Sanguigno with Poncirus. I got only one tiny seedling with trifoliate leaves. But it died. I shall try again. I pollinated V. S. with N1triVoss. One possible hybrid so far. But leaf form is not so distinct that I can be sure it is a hybrid. Then I pollinated F. margarita with V. S. Two seedlings out of about 20 pollinated flowers. Both seedlings were very sensitive to root rod but I saved them on Poncirus. One grows well, the other slowly. They seem to require warmer temperature in order to grow (not as extrem as pure Kumquat). When I have luck, the first plant may flower the coming year. Why I am sure that I have produces hybrids with Kumquat? Hmm, the seeds were much bigger than normal Kumquat seeds, both seedlings were thorny and the leaves are smaller than oranges leaves and have a tip.
I also tried to cross Chandler (Siamese SWEET x Pink Pumelo) with Poncirus (--> no seeds ever), Poncirus with Chandler and Poncirus with C. limettoides. The latter crosses have not yet germinated.