Just sharing here my opinion.
The downside of adding more Chinese, Korean, UAE, etc. teams is that they end up some times in the same group in AFC CL.
Good CSL missing teams in PES are Hebei China Fortune and Shanghai Greenland Shenhua in my opinion.
As for K. League, I would say Jeju United and Ulsan.
The other possibility that wouldn't screw up Afc CL is to add teams that failed to pass qualifiers such as Hanoi T&T, Muangthong United, Johor Darul Tazim, Kitchee, etc.
But these teams are quite weaker than any Chinese, Korean, Emirati team...
As for Indian Superleague teams I wouldn't bother too much as it's not recognized by Afc and Fifa. It's just a small yearly tournament that lasts few months.