I think I am able to formulate my concerns more clearly now. Keep in mind these are just out loud thoughts without intent to persuade anyone. This is your mod and I won't cry if this won't get into it.
Point of view #1: formal fairness
Game engine is a platform providing (theoretically) equal experience to either party. Besides, in turn based strategy, such platform should also be a storage of all the data pertained to each party and should provide them on demand at any point unlimited number of times as needed for the party to make a decision. The great example is indication of spotted enemy unit. Once spotted, the engine provides this information to both AI (in form of variable stored for the whole duration of AI turn) and human (in form of visible figure on the battlefield). Player can save the game at this moment and return to it in a year and still have access to all information available to them to take a decision.
The knowledge of the "attack origin" is not like that. Engine indeed saves it and makes it available to AI for how many times it wants to recheck it but not to human. Player has to be very sharp in marking all attack origins in memory, then be able to remap all their visual cues to the actual map, and maybe even draw a paper map for themselves so multiple locations won't fall from the memory, etc. I hope the point is clear.
Point of view #2: playability
Besides the chess like mind wrestling, ground combat is still part of bigger game that has to be playable to be attractive. With this in mind it is probably wise to not introduce any super strong or super weak strategy/exploit to not diminish importance of other game elements. Otherwise, it turns into one trick pony getting boring very fast.
Ability to detect when opponent's unit shoots, throws anything (including smoke grenades, flares, grenade relay, or even just passing equipment to each other), or even simply drop some unneeded equipment, or just fart - seems like such overpowered ability. Heck, it is now dangerous to even freeze in panic or become unconscious letting your weapon rolling out of your hands. Meet the grenade next turn and your unit is dead.
Such extra detection outweighs spotting by order of magnitude in quantity and efficiency. No distance limits, no visibility limit, practically whole player squad can be pinned on a map without even approaching enemy. Makes other risks tiny comparing to this one.
I absolutely welcome smart AI making me utilize each and every bonus in the game, maneuver, use tools, get prepared, research, get visual cues, compute in memory, etc. However, when most of the time battle can end in 1-2 turns it kind of ruin playability and interest in strategizing in general.
Here are few thoughts what can be done about it, should you be interested, of course.
If you want to keep it for AI it would be nice to show same information to player in permanent manner. Like arrows after detecting movement on the scanner.
Other option is to blur this information to AI imitating not exact human perception. I.e. introduce random location error or something. More difficult, I think.
Maybe reduce AI perception to see such event within certain range.
Since AI units rarely drop things, use smoke grenades and flares, maybe exclude these events? If not all of these, then maybe only dropping items? Otherwise, unconscious soldiers will become dead in a matter of seconds. No use in saving them (will just lose a medic as well).
