On "Corp, Scale and Till" effect, "Scale X(スケール X)" setting value is ignored when I used Japanese language setting. Insteed,"Scale Y" works for scale X and Y both.
Similar issue is reported here with Arabic on Windows. https://forum.kde.org/viewtopic.php?f=270&t=156615. Can you test the following: change your keyboard language to English and test again.
Comma point issue is fixed with version 20.08.0.