<<The notice indicates that the SEC staff has determined it may bring a civil action against a person or firm, and provides the person or firm with the opportunity to provide information as to why the enforcement action should not be brought.[2] The person or firm is generally given 30 days to file this response in the form of a legal brief considering legal and factual arguments as to why no charges should be brought against them.>>
Like all civil matters, a person can negotiate with the (allegedly) aggrieved party, in this case the SEC, and settle the matter with them before a suit is filed.
That's not true.
> They’re civil enforcement so they can only pursue fines and injunctions
A lot of SEC things are both civil and criminal, and while the SEC doesn't file criminal charges, it does send referrals to DOJ. So, yes, though there are more steps before it gets to jail time, disputes with the SEC do carry that risk.
I believe you can file an action seeking a declaratory judgement, but as I understand there is generally little reason: a Wells Notice is not, as I understand it, a “we might sue you if you do X” thing but more of “our staff have determined you have done X and that we should sue you for it on basis Y, but you have an opportunity to submit a legal brief to convince us that our staff are wrong before we approve their recommendation” thing.