Hello @kaspt ,
Thank you for your post. I will answer your questions one by one.
1. Debugger: The KEA series MCU supports the PEMicro universal multilink. However, in the Supported Devices section of MCU Link JTAG/SWD Debug Probe | NXP Semiconductors, I didn't see that it supports the KEA series. The St-Link is not our product and should not be available.
2. Flash software Tool: You are correct that PROGDSC for NXP DSC does not support the KEA series.
3. IDE: According to Kinetis EA Sesries Family of Microcontrollers - One-Pager, the supported IDEs include CodeWarrior Elipse, S32DS for ARM, KDS, IAR, and Keil.

I would recommend using CodeWarrior and S32DS for ARM more. They are free software from NXP that integrates programming, debugging and flashing functions. It can be used together with universal multilink of P&E.
S32DS for ARM: S32 Design Studio IDE for Arm® based MCUs | NXP Semiconductors
I understand that you have already downloaded CodeWarrior 11.1, so I recommend that you continue to use it. It can be confirmed that CW 11.1 can work properly on both Windows 10 and Windows 11. As for the problem of the error when creating a new empty workspace, let's see how to solve it together!
Hope it can help you.
Best Regards,
Celeste