You seem to heavily overestimate the possibilities of visual modding. You can put a circle with the base line of sight around a unit. But since line of sight is dependent on multiple factors (age, techs, civ, …), these circles woudn’t provide any useful information and would only obscure the vision.
In terms of build order live prompts, this is completely impossible with visual mods. There exist such scenarios to train the build orders, which is completely fine. But as you get more experienced, you know your build orders without having to think. So even if there would be such things, it wouldn’t affect competetive play and would only help beginners.
Also in a competitive game, you have to adapt a lot to the circumstances. Oftentimes, it is not clear at all, what the right decision might be. So, relying on an AI that tells you what to do wouldn’t deliver great results; at least not on a decent level.
Many people here seem to have a lot of fears about the future of our game. However, most of the things you fear are not possible without data mods or some additional software (which would indeed be cheating).
Restricting modding is in general very unlikely a good idea in any game. Also remember that Forgotten Empires has started as a mod! So without mods, there wouldn’t have been any DLCs and the Definitive Edition would probably have never been developed.
As long as there isn’t a significant reason, I would shy away from such things as a “white list”. Why would a modder invest dozens of hours, if he can’t be sure that his mod makes it on that list? And what would be the criteria for a mod to get on the list? Not to mention all the bureaucracy to inspect hundreds of mods (including the many local mods) and possible arbitrariness of the poor guy, who has to decide this! All this trouble, just to achieve - to achieve what exactly?