The most up to date information I can find on raising baby Chinensis recommends treating them like juvenile Laotriton.
Basically, damp paper towel substrate with a pile of leaf litter at one end for hiding. I've used the same method for Japanese Cynops species and it works very well. I normally offer chopped small nightcrawllers, whiteworms or live bloodworm with multivitamin supplement to terrestrial babies and havent had any problems. I've no experience feeding roaches so I don't know if they will catch them, but unlike Laotriton they will use their tongues when hunting so it's worth trying for sure.
Good luck with them, I think Paramesotriton will become very scarce in the hobby now the wild caught adults are drying up.