Learn English – an alternative word for ‘repercussions’ that has a positive denotation rather than a negative denotation / connotation

For a physical object, "damage" is the usual choice in my experience. For software, you sometimes see "corrupt", though that usually applies to data and not the product itself.

When milk has not gone bad (become spoiled), the word I invariably hear is "good," as in "the milk's still good," or simply "the milk's good." (People also say, "It hasn't gone bad," but that doesn't utilize the word you're looking for.)

The same statement, the milk is good, can also be used as a statement of the milk's quality, and people know which one you mean simply by context and circumstances. (Another way of distinguishing this other use of good is that when we say the milk is of high quality, we have a tendency to phrase it differently, thus: that (instead of the) milk is good or that's good milk.)

Edit because I forgot to answer your second question: I don't consider "on" or "viable" to be viable options in the least. :)