I am an unfortunate victim of that situation (banks would lend in local currency but would lend in CHF). It turns out banks didn't actually go and buy CHF to give you, it's just the way the loan was written as what ended up in developers bank account was local currency anyway.

So in that specific situation it was entirely possible for a gov to intervene without resorting to buying foreign currency. In my country they still didn't, in Hungary they did.