My take on this is that even if China had been 100% transparent, Western countries were never going to act until it was already too late.

A serious pandemic (or mass deaths of any kind) is something that most people in this part of the world have not experienced in recent history. Therefore while the facts were known I don't think the risk was ever tangible for Western countries in the way that it was for Asian countries such as Korea or Hong Kong that had been through SARS.

And because the costs of shutdowns and travel restrictions are so high, it would be very difficult for Western societies to take these actions until the costs of not acting had already become apparent.

Unfortunately due to the nature of a virus outbreak, at this point it was already too late to avoid mass casualties.