It's all here:
https://docs.google.com/spreadsheets/d/1ThjsXsz1N7R-JtSJsXl8w9ir8CrHui7ifHIXKwTCqfI/edit#gid=0
Okay -
the Ancient Ruins are built on a planet that spins ANTI-CLOCKWISE - I'm of the personal assumption that this is important to the Guardians on location picks, and their home world may spin anti-clockwise.
After narrowing down the results in all systems, out of ALL the planets combined in ALL FOUR systems, ONLY FOUR planets have an Anti-Clockwise spin!
Further narrowing down these results, I have only picked the BEST TWO results, below:
Systems and planets matching Ancient Ruins criteria:
Synuefe XO-P C22-17 D 1
Synuefe ZL-J D10-119 11 B
The following did not make the cut:
Synuefe XO-P C22-17 AB 1 - planet radius too large, too hot, is a High Metal content planet (not rocky), higher gravity, a lot denser.
Synuefe XO-P C22-17 AB 3 - like AB 1, very similar in all aspects - not at all similar to Synuefe Ancient Ruins.
Based on the evidence, I think Synuefe XO-P C22-17 D 1 and Synuefe ZL-J D10-119 11 B are THE BEST two candidates to search for ruins!