I personally have only seen 1 fire event and I don't even in think its related to yours. It was the Theater Burned down event. Is that linked to your fire events?
nope.
I think that the problem with the Fire events is not that the minimum Flammability thresholds are too high, but that the probability of a Fire event being triggered is too low. Even when my cities have high levels of Flammability, nothing ever seems to happen.
To answer your question, not really, I have only ever had one event involving fire, where my Marketplace burned down. It had almost no impact on my gold reserves at the time to rebuild.
You asked for it
I'll just triple their chance now.
Edit: just noticed that one had its chance set to 5 instead of 625 anyhow later today there will be an update to the svn with tripled chances...