The ideal inflation rate is agreed to be around 2%, but I think that it doesn't matter as long as there is inflation in the first place and the continuous price changes remain positive instead of negative over time, even if those price changes are minimal, it's not a big difference.
But if it turns negative, China has healthy interest rates of 3.5% and could just lower it a little bit to drive consumer demand and break the deflation again, or give some government stimulus with QE from the Central Bank.
Despite what delusional freaks blabber about in the West, China is still way less indebted and way healthier than the West even with recent developments, it can still afford way more debt without going overboard. It just recently started utilizing debt more freely after decades.
Regarding the fear that it will weaken the currency too much, I don't think so. If anything, the yuan should've been suppressed artificially for a long time. But due to the current process of internalization by the CB, after many decades, it will naturally appreciate over time finally.
And, if everything else fails, China has the most efficient governing system in the world with absolute power, authority, and capability, and could use tactics to increase consumption we probably never even thought of before, like the social credit system, or something entirely else.
To be honest, where have you ever heard of any country in history being worried about deflation while projected to grow 5% a year? Deflation is only bad when it causes a drop in productivity, other than that it just means that consumers are paying less for more stuff.
To further add, China would grow even more, in my opinion, around 7-8% this year, had the West, their main customers, not been in recession/stagnation. And it is still 5-6 times bigger growth than them, depending on the country, even if it is 5% GDP growth.
The current problems in the world economy are not caused by deflation in China, and similar bullshit, but by inflations, stagnations, and recessions in the West. China is the effect, not the cause of that process. That's what those bullshitters don't understand, the causality.