Choosing a side in the Venezuelan crisis would mean the total invalidation of China's previous policy of non-intervention on other states. Not to mention this will most likely be the first step of a slippery slop down a similar path of foreign entanglement and imperialism not unlike that of the US.
While US back regime changes are deplorable and almost completely insulated from the public masses of the particular country that is "supposedly" for their benefits. It is not like backing up Maduro at this point is going to make anything better. Suffice to say Maduro's Chavez policies aren't rooted in the standard 101 of How 2 Economy and by and large his support is not complete especially if the legislative body of Venezuela can act in opposition to him.
It is all about the public image if one is too be seen as a "responsible" power, and at this point the Venezuelan Crisis has been charged to the point of damned if you do, damned if you don't. China's economic investment in the Maduro's government policy and Guaido's unbashed wooing of Beijing's support means that no matter which side China intervenes for, it is clear that the public both domestic and international will see it as being mostly in China's own interests.
And there is the issue of legitimacy to be considered, unlike the Russian intervention in Syria which was on behest of the current acknowledged government. Venezuela's government is currently in confusion and anarchy. So neither side can legitimize any action China could possibly make. That makes it a prime excuse for any other country to seize upon.
And finally there is the whole military capacity to begin with, Venezuela is far in what is considered to be the US' backyard, so China cannot expect to have as much leverage as Russia could have done in Syria with a similar number of troops. Morevere, Russia's Syria intervention was done with speed and guile, 2 things which are impossible for China to mount in Venezuela due to the sheer distance and lack of infrastructure or forward deployed forces. Any potential Chinese intervention force would be met by an opposing US flotilla on the excuse of "self-determination for the Venezuelan people" which would be ironic considering how China use to harp that tone alot in the past.
So the best thing that China could do would be to support calls for a re election that is supervised by a independent body, all the while making assurances that the losing side would not be subjected to revenge politics.
Venezuela would be the perfect stage for China to demonstrate that it's policy of non-intervention and equality actually holds water. If Guaido comes to power via free and fair elections then China should acknowledge the results like how it did with Malaysia.
Nonintervention itself is kind of irresponsible, China needs to rid of that.
I think you are confused with China being responsible as to what the West expect to it to act to preserve the Western order of thing.