terminal – Unable to reinstall MacOS Mojave on a hardware modified, mid-2012 MacBook Pro

I decided to reinstall Mojave onto a mid-2012 MacBook Pro that I purchased second hand in June 2020 & modified some of the internals of*. I have a lot of files from previous backups of files as well as from the last time I used Windows in 2018, & it was beginning to get a bit glitchy. While I did follow the instructions on the Apple website to make a bootable USB stick with Mojave on it with Terminal, I don’t think that I formatted the USB correctly.

It also gives me an error that says “This copy of the Install macOS Mojave application is damaged and can’t be used install MacOS.”

The previous owner had installed Catalina onto it, but I’m also an artist who needs 32-bit app support. Last year, I managed to get a USB stick with Mojave on it working (I currently don’t have access to it), but I’m beginning to think that’s why I can’t reinstall Mojave.

Terminal tells me it’s on Bash version 3.2. I’ve tried internet recovery (which has never worked with this machine), & changing the date to some time not long after Mojave’s original release date.

I’m at a complete loss.

*I replaced the original, failing 750GB HDD with a 2TB SSD; replaced broken super-drive with a SATA adaptor & a 1TB SSD; increased RAM to 16GB; replaced depleted battery with fresh one. I didn’t buy them all at once.