The key to your argument seems to be "The IRS can do a look-back IF one gets a 1099-C but fails to declare the income." That is true and there would be no excuse on the taxpayer's part for ignoring the situation.
The main implied question, however, is a different one: "If one does not get their copy of the 1099-C but the creditor submits one to the IRS, could the consumer/taxpayer be facing severe penalties for "evading" taxes on such a debt although they had no idea they even owed the money?"
Another implied question: "If that were the situation, would the consumer's financial situation at the time the deficiency is discovered be the one considered, or would "solvency" or lack of it be based on the situation for the tax year the 1099-C was actually issued?"
In the first case, the IRS will want their interest and penalties AND the tax and will book no excuses, even a reasonable one like the taxpayer did not even know they owed that additional tax due to no fault of their own.
The second case--which tax year's situation would apply in determining whether the taxpayer can declare themselves "insolvent" or not--is not so easy. Logic would say the situation existing during the tax year when the deficiency is actually discovered would be controlling. Logical, and possibly wrong: The IRS' idea of "logical conclusion" and ours may well be two different things and guess whose "conclusion" would rule?