I've noticed that the cloth map does in fact reflect the type of terrain in a tile.  However it's too hard to make out as it's implemented now.  So far I've made out Black, red and a yellowish green.  Swamps seem to have a dull brown.  But all these colors are too subtle to notice out of hand and some are too similar to quickly distinguish between them.

Also should you kill a soverign and their city dissappers the tile coloring reverts to unrevitalized rather than remain fertile/desolate.  I'm unsure if this is intended or not.

Lastly there's some tiles denoted as swamp.  it shares a similar hue as revitalized land and yet you can't build a city there without expending essence.  On the other hand you can build cities around fountains without expending essence at all.  Both share the same tile coloring. Which makes it confusing in terms of what's acceptable land and whats not when building a city outside your influence ring. 

My suggestion is just be a bit more blunt with the use of coloring on the cloth map.  As it's far too subtle as it is now.