[RESOLVED] should I be concerned by the output message "script succeeded: result was [256]"?

[Lopolin]

It's my first time Installing a custom ROM, I chose the Xiaomi.eu Stable ROM. I have a POCO X3 Pro (vayu) and installed TWRP 3.6.2 to then Flash Xiaomi.eu MIUI14.0.3.0. I was switching from MIUI Global 12.0.5 (or was it 12.0.0.5?). I have encountered a few issues along the way and probably did a few mistakes... After flashing the ROM and Clearing the Cache I am now almost finished. the only thing I need to do is reboot into the system, but before that I saw a few things in the log that concerned me, and probably a few other issues too:

I flashed TWRP NOT using the toole here, but rather using the one on the official Android Developer Page
the flashing also took less than 2 minutes... or even less than 1 minute...

Let's start with the log (as far as I can remember without issue):
script succeeded: result was [256]
Failed to mount '/system_ext' (Invalid Argument)
Failed to mount '/product' (Invalid Argument)
Failed to mount '/vendor' (Invalid Argument)
Failed to mount '/odm' (Invalid Argument)

am I safe to reboot?

another Problem I noticed was I couldn't send the ROM I wanted to install to the /sdcard path, so I sent it to the /data path instead usind ADB because my Windows Explorer didn't recognize my phone correctly. Problem being that was after I Wiped ALL Data. I did that by going in Wipe > Format Data. So might this error be caused because I wiped all data?
Another Issue is if I go to the mount section in TWRP and try to mount the Internal Storage it aswell says "Invalid partition selection". I don't think that's what was supposed to happen. Data, Metadata, Cache and the others work fine, or at least they can be selected unlike Internal Storage.

Should I rather reboot into Fashboot and flash the Xiaomi.eu ROM via that?
Do I need to use ADB to remount the missing partitions?

How do I fix those errors? Are those errors normal?
I don't want to reboot into the system just to find out I bricked my phone.

Can anybody help me please?

Thanks in advance.

 

[Lopolin]

I booted into fastboot and flashed using it. I saw this thread and thought that instead of risking booting into a broken system i use Fastboot and the .bat Files within the .zip to flash it.

I'm pretty confident that if the exit code was 0 I could've booted into a functioning system, because from all the threads and answers I saw here I think that the mounting errors that I encountered are not a problem at all. If it would've been something like /data then it definitely could've become a problem but the ones I had probably aren't.