The AI may or may not have the same range that I have because they may have different abilities and research different techs. That is not the problem. The problem is that seem to ignore the range limit and send ships across the galaxy. This is most obvious on Huge and Gigantic galaxies if you start near the edge of the galaxy. The AI on the opposite side of the galaxy will send freighters to your planets when your freighters can't even reach the center of the galaxy.
When GalCiv3 first came out there was a problem with AI on the other side of the galaxy declaring war on you then doing nothing. This was because they didn't have the range to reach you and didn't know what to do about it. This was solved by teaching the AI to build starbases to bridge the gap. They were very good it. In Crusade the AI on the other side of the galaxy will still declare war on me, but now they can reach me without building starbases. I can't reach them unless I build starbases.
Once I had what I thought was enough evidence of the AI ignoring range limits, I reported it on Ticket BKL-489-10361 in December.
When it comes to the AI being dumb or not seeing everything, I believe they don't see everything, at least most of the time. I have settled planets that were near an AI starting star system that the AI could have settled long before I got there. I feel that means they explored in the other direction and missed the planets, just like I have done more times than I like.
The situation where an enemy AI ship can track one of my ships all over the galaxy seems to be different than just seeing everything. Once the ship decides to attack my ship, it seems to know where my ship is at all times and can follow it anywhere.
But several times already, I've done a sharp turn to port or starboard while outside of their FOV and they'll make that turn with me immediately. If I turn back, they'll turn back.
Their FOV is 2. Mine is 11. They can move 4 tiles, I can move 7, 9, or 11, depending on ships used and fleet compositions. I'm not so close to them that they should be able to guess THAT easily and THAT accurately all the time, every time.
That is what I see. There is no way they should know where my ship is, but they do. I can make multiple changes in direction or stop for a few turns, and they still come directly at my ship. This is not the same as the AI seeing everything. It is one AI ship following one of my ships everywhere.
I do need mention one time in the original GalCiv3 where it was "obvious" the AI was cheating and seeing too much. I was attacking the Iconians, and they always seemed to know where my ships were coming from. I eventually noticed the icon of a scout ship when I was zoomed out. That shouldn't have been enough to let them see me, but I clicked on it to see what I could find out. I was shocked when the type of scout was Iconian Spy Ship! That was a ship I had designed several games earlier when playing as the Iconians, and it had a very large sensor range. So, instead of cheating, the Iconians were using my own ship design against me! I was somewhat embarrassed. I didn't solve the problem by destroying the ship because they had at least one other Iconian Spy Ship. We eventually made peace.
I mention the Iconian episode because the AI can be tricky at times as it uses what is available, so a Human needs to be very sure before accusing the AI of doing something it shouldn't be able to do. I have been careful to make sure I am actually seeing what I think I am seeing, so I feel sure that the AI sometimes does some things it shouldn't be able to do. This is what I have submitted tickets to report them.
I guess now is a good time to mention that the AI ships ignore movement penalties that some tiles have. This includes asteroids, all types of nebula and tiles in the area of effect of starbases belonging to races that have the Vigilant ability. This is also included in Ticket BKL-489-10361. This did not occur before Crusade. I think this and the unlimited range problem are like the money bug that appeared when Crusade was released. The money bug was noticed quickly and fixed, while the movement and range bugs were noticed recently and have not been fixed.