So first, keep an array that is indexed to match your grid. Lets say the first column is 0 through 9, the second is 10 through 19, and so on. You know that clicking on the bottom corner tile will always give you index 0, the top corner 9, and so on. Then, for every array that needs to hold map data, ensure they all match your data structure. For me, that looks like this:
I have a few dozen arrays that hold every bit of information about the map. 1 for temperature, 1 for precipitation, etc.
So you could keep arrays with the Instance Type(Green), and its reference Index.
Spawn an invisible collision mesh at every tile that is the same size as your instances, and is indexed in the same way as the rest of your map data.
When you click your map, you hit your collision volume, break hit actor, find hit actor in the actor array, get that actor’s index, and then use that index to get any information about that tile you need.