Need help with COL-L29 (Honor 10)

[SeekingHelp]

Hello,

As stated in the title, I'm running into issues trying to downgrade my Honor 10.
There's kind of two issues involved, one being that dc phoenix doesn't register the device in adb (despite it being listed under .\adb devices and enabling USB unlocking).
The other (for testpoint activation over fastboot or update mode) is that there seems to be come issue downloading CURVER?
This is the error I get:

Error downloading file Columbia-L29D_9.1.0.325 (C461E2R1P9T8)_Firmware9.0.0_r3_EMUI9.1.0_05015CHN _FRP_bypass_2.dtwork, partition:CURVER

This is the case for all firmware files compatible with my device.

I have installed hisuite and the testpoint drivers.

My apologies if I've overlooked something obvious like needing to go into the system settings (The OTHER system settings?) and pressing the big red "Allow this" button.
I am not usually a Windows user and this is, frankly, reminding me of why.

I really hope to get help with this soon since I only have 2 days left on my license. Probably closer to 1 1/2 now. :/

[SeekingHelp]

Adb sort of worked once, in exchange it failed to detect the device in update mode.

TBH I'm still looking for help because I have frankly no idea what else do.

[Valdemaras]

Sadly we do not have assistance with downgrades. Usually, it is done via HiSuite though.