ST2130 is copying ETA 2824 (vastly used in Swiss and German watches)
Here is a thread comparing TY2130(I think it's the same as ST2130, only difference is being sold by HK seagull not Tianjin seagull) and ETA 2824 (and Hangzhou 6300 as well):
How do Seagull and Hangzhou compare to a ETA: An in-depth look...
ST2130 is more stable than ST25, but now almost all complicated seagull watches are based on ST25 mvt. I never see a ST21 seagull watch with complications but only the date here in China, I don't know how about the abroad market. I heard that ST21-based complicated watches still during researching and designing.