Can you elaborate on what might be meant with the FPS comment?

こんばんは。
Good Evening

よ～～～し次は１５ｆｐｓだな
OK~~~ so next is 15 FPS
技術的には15fps自体を実装することは可能です。
Technically it's possible to implement 15fps

ただし、まずはパッチ1.19にて30fpsをお試しいただければと思います。
However, first we would like for you to try the 30fps in patch 1.19.

PCの環境は人それぞれ違いますので、フィードバックをいただきながら、
その上で、15fpsの実装検討を含め、快適な動作のために対応は継続して行っていきます。
PC's environment varies depending on the person, therefore we would like to receive feedbacks first then on top of that be able to look into releasing 15fps and continue to make other changes which may ease (make it more enjoyable) the play.

The game's framerate is already uncapped meaning it can hit 60 fps or higher. All most want is for the game to be optimized so its not unnecessarily taxing on hardware that should be able to maintain a steady 50-60 easily. I know its just a quick translation, but it just seems odd to talk about implementing a specific framerate...especially something like 15fps.