Final Cut X is constantly crashing or blocked thinking since Ventura update

Does this happen without the plugins? Can you test on a new admin user?

Please post an EtreCheck report https://etrecheck.com giving the application Full Disk Access in Privacy System Preferences. Copy the report and use the Add Text button to paste the result into reply box. 

Did you give EtreCheck full disk access? It's not showing space on the external drives.

What did you do the speed test on? Using what software? Black Magic? Those numbers are pretty slow for video work.

Did you test the application in a new admin using without Nitrate and Color Finale?

SSD, you don't mean the internal system drive, do you? That should have read/write numbers that you showed. HHD, you mean the Western Digital My Passport? That should be the slowest drive. Both the T5 and the T7 should be faster.

If being unable to delete files happens frequently, I'd restart the machine and hold down the shift key until the login screen appears, also known as Safe Mode. While booting into Safe Mode it might take a little longer as it runs a file system consistency check, repairs any issues it finds and rebuilds some system files. Login, then Restart again but don't hold the shift key to boot normally. Hopefully this fixes being unable to delete files.

That will definitely be fastest of your drives off you have space on it.

Even if the drives are slow they really should not crash the application.

It should be a fairly obvious thing, but just in case it was missed (I did not see any mention here in this thread): does FCP have Full Disk Access in System Settings?