For what it's worth, OP, the server upgrades SE has implemented so far seem to be no more than their emergency measures to make the game playable. It's stated that they're still working towards a full upgrade of their servers in Yoshi-P's recent announcement:

Quote Originally Posted by Naoki_Yoshida View Post
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Following the increase in server capacity, we reached 325,000 simultaneous logins, and we anticipate that this number will only increase. Therefore, as our development and operations teams continue to work towards a full-scale upgrade of our servers and systems in order to accommodate more players, we will continue our suspension of digital sales of the game.

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Bolded for emphasis.