Well, that is not a bad idea however you can already do such a thing by simply
looking up only one chest type at a time.
I considered something like this a while back because I was going to change the
letters in the icons to numbers that showed how many of something was in one
location (aka, only look for Gold ore that is bigger than 10 then it shows as 16
on the map. However, 16x16 is the size of the current icons and that's very little
room to be drawing a two digit number in.
I figured as long as I had the number system in I'd use it for the chests as well.
As of right now the best way I can think is with a right-click menu on the chest
filter list and then just add a #1 to the end of the item text in that window.
Granted, I'd need to have to find a way to handle when there are more than
one tracked object in a chest.
Using this type of system I could probably fit 1-9 into the Chest symbols but it
would also conflict with my plans to show the chest type (gold, gold locked,
shadow, shadow locked and so on).
I'll give this some more consideration.