@Anonymous
Hello, I found it that the Power Automate for Desktop does need user to install the English package, but not necessarily to set it as Display language, only need to drag it up as Preference Languge:

in my case, originally I only have the Chinese and Japanese Language Package,
after installing English Package and move it on top of the list (Windows will identify the first language in the list as preference language),
Power Automate successfully changes to English while system display remains Chinese.

Hopes that this will help!
順遂
______________
臺大機械系
伍恩輝
En-Huei Wu
Department of Mechanical Engineering
National Taiwan University
No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan (R.O.C)
E-mail:
b08502028@ntu.edu.tw