Hi Ante,
What do you mean by polygon meshes ?
The setup as in that image shouldn't be affected by the number of sides per face.
Where things do get trickier is if you have multiple meshes. Then you need to split the list from locator index into separate parts.
Regarding how Kangaroo handles data trees - right now it doesn't. Or rather it will just result in multiple instances of the Kangaroo engine, which is not a good idea.
The new version we are working on should be able to take in a tree of mixed geometry objects(eg meshes, curves etc) and output the same tree structure with the same objects, just with their point positions updated, so no need for the whole ListIndex business.
I'll send you a testing version as soon as I can
best,
Daniel