As @UKresistance rightly mentions, the AI has no knowledge on what is going to be dropped next on the board. The AI will make a move based only on what the player can see, the board and spells it can cast. There isn’t even any code in there to line up any further moves or check for cascades, and as much as I would love to add that into the AI, I know that all it would cause is more complaints about “Cheating AI”, as much as it would then be closer to a smarter human opponent.
The hard part about mana generators is that it is something that both the AI and the Human player can do outside of just playing the game. I can confirm that it is running the same bit of code to drop gems down if it is a board match or from a mana generator, although by having more gems move on the board, there is bound to be a “higher chance” to get matches, kind of like rolling one dice compared to 3, 5, or 10 and hoping to get a 6 come up. If we did “nerf” these spells, it would have to affect both the AI and the player, which would be negative on both sides.
Thanks @HADuke for posting the video, although as others have mentioned, looking into a 48 minute video is quite impractical since we would like to spend that time working on adding new features and fixing bugs instead.
As for the points you did bring up, Mana Surges are dependent on many factors, including player level, guilds and kingdom levels. Having players get Mana Surges more often generally means they are in a higher level guild, where their chances are improved. Looking into leveling up guild statues would help bring you (and your guild) up to get more mana surges and improved troop stats.
For percentage chances, as mentioned by @HKdirewolf, this is all up to chance. For example, when rolling a dice, if you roll a number, it is not like that number will not appear in the next 5 rolls. You could get a streak of sixes, or a streak of ones, or just a random smattering of numbers in between. If someone rolled a six five times in a row, is that cheating or is it luck?
As for everyone that is concerned with these chances not appearing to be working correctly, I am giving you homework. Please read this article, all nicely put together to explain probability, especially on chances seeming “wrong” - http://www.abc.net.au/science/surfingscientist/pdf/lesson_plan19.pdf.