Insolvency means that they owed 220 billion, while owning 200 billion worth of assets.

SVB had enough cash-on-hand, and could borrow money against their assets in order to serve 42 billion dollars worth of withdrawals.

Their balance sheet still had a huge hole, from the moment that they marked-to-market their long-term treasuries. Which was before those 42 billion dollars were withdrawn.

I'm being very specific here, they had ~175b in deposits. There assets may or may not have been more or less than deposits, that is immaterial. They were insolvent because they did not have enough cash/credit/liquid capital to cover the predicted withdrawals. That is the why they are insolvent.

Long term, yes, the asset state would have been a problem, and would(should) have been marked up as a ~25% loss on the bonds that were being hammered by inflation.

but at no point would that have been a big issue for the stability of the bank. It would have hammered their share price, but not deposits. It probably would have required a change of management, but again, not fatal.

The issue here is that "asset insolvent" is rarely described like that, it normally at the point where you declare bankruptcy because no-one will buy you out because you liabilities are way more than your income.