[Drizzleqyy's THIRD CACHE SERIES]

While choosing the route for the second ever CITO event in Guangzhou (GCAYXPZ), I noticed a huge gap along the Xibiankeng River. The northern part and the southern part were intentionally separated by @michael_gz. Thus, as I fill up the gap, I try to follow the "innovation" guideline by @michael_gz, hiding a unique mystery cache in the series.

So here comes the mystery cache!

If:

newest & largest ⬇️=(11, 24)

⬇️=(16, 30)

⬇️=(18, 34)

Then: 

⬇️=(ab, cd)

↗️=(ae, fg)

最終の座標：N 23° a1.(b-4)(c-2)(d+8)' E 113° 24.a(f+5)(e+4)', Error = g meters

You can validate your puzzle solution with certitude.