'Tiz a good idea that 
Traitstone Search & Sort Feature
How easy to implement it is another matter entirely; looking at the structure (from a Db perspective) it seems designed from the ‘troop’ being the primary key, whereas what I think would actually be more helpful is the traitstones being the key.
So rather than the current “I have a Gloom Leaf let’s see what his trait requirements are…” You would have a “I have an Arcane Beast traitstone show me what troops have this requirement…” etc.
An interim measure to this might be to simply allow the display of all 3 tiers of the troops trait required list in its current form to at least give players a heads up on what the overall investment required might be for their chosen troop(s)
I know that some of this can be gleaned by browsing this forum and the great external user supported sites/wiki etc. but some basic info should really be available within the client itself, especially when you’re potentially making a decision that may represent a few weeks worth of effort (given current drop difficulty of higher stones) for the average player.
Before I get shot down and accused of elitism using the ‘average player’ monicker I simply refer to my own scenario;
My wife also plays a few games a night as it helps her get off to sleep… 
She only gets rank 1 PvP every now and then, and very rarely gets the weekly event troop.
This is opposed to myself who try to reach rank 1 on reset day every week and I always buy at least one of the weekly troop (6 this week 
)
Recently she asked me to help her complete her traits for Jarl Firemane and we went through exactly the same discussions on searching stones, filtering choices and how you can be certain of spending your limited stones wisely.