"Bricked" is a vague term, which means different things to different people, so doesn't really help us much. Tell us how you tried to downgrade and at what point in the process it failed and we'll have a better idea what is likely to be the problem.
However, the fact that it responds to fastboot is significant. The phone will only respond to ADB commands if it is booted into Android and USB-debugging is enabled, or else running a custom recovery with an ADB daemon. Conversely it will only respond to fastboot commands when booted into a particular mode (fastboot mode or download mode, depending on what phone you have). There is no mode in which it will respond to both. So the fact that it responds to "fastboot reboot" suggests that it's booting into fastboot mode rather than android, which implies to me that the system software was so badly damaged that it won't even boot into recovery (or maybe that whatever key(s) you press on that phone to boot into fastboot mode are stuck - I have seen that happen to some phones). If you flashed the wrong firmware or interrupted a firmware update this is possible.
So my best guess is that you'll have to reflash the phone's firmware. The good news is that on the phones I am most familiar with (HTCs and Pixels) fastboot mode is where I'd want to be to do that. But I don't know the tools or procedures for a Huawei.
But one more question: what exactly do you mean by "skip the Google email in the setup"? When I first read that I assumed you meant when configuring the phone after booting into Android, but if you had managed to boot it I can't think how you could get into this state. The other possibility is trying to bypass factory reset protection, but the way to do that is to remove the account before resetting the phone.