@mitu Yes, it is!

So I thought I had better post to say that I solved my own problem. I had to get sync from SCART pin 19 on the Pi2SCART's female connector, not pin 20. I did not know about male SCART leads swapping pins 19 and 20. I hope this post might help somebody else out one day.

@mitu
That fixed my problem - thanks for your help.

I've just made a donation to Retropie because it's my favourite community project and your help, although a bit tart, was faster and more useful than any paid support I've ever received.

My apologies, next time I post I'll be sure to put in all that information.

However, on this particular problem, I realized what the issue was... I hate to admit this, but in trying to switch from composite input to RGB, I was selecting the wrong input on my PVM. I actually cannot believe that I was that stupid, hahaha... that was several hours of troubleshooting down the drain because I apparently couldn't be bothered to double-check that I was on the right input!

In any case, thanks for your reply, but I managed to figure my stupidity out on my own!

I see! The screenshots from your link really do show the difference. Thank you!

We don't support 3rd party images - https://retropie.org.uk/forum/topic/3/read-this-first. You already opened this topic a few weeks back and from what I've seen, there's more than just the pi2scart that's configured on the image - including RetroArch.
You can either start with a stock RetroPie image (and configure pi2scart only through /boot/config.txt) or use ask the image authors for guidance.