Testing were made by @anoek himself, and I think reported in this thread
there are dozens of threads and opening again the subject without bringing some novelties may be unproductive. maybe first check first all that was written on this?
Maybe post this critic in the thread with the data. Would be much more productive
Seems you found a good way to manage your matchmaking with multiple accounts. Even if in some cases using the global ranking may create some distortion, remodelling the system is not a small work and would come in some priorities list. (And seems low now)