I got fed up with eating sweets so I had a bit of a play with this one. The results were pretty much as expected in that the grad map shows that where red is pretty flat and it is going to struggle to get long thin rivers here. Where its black its dead flat so its obviously going to pool water in that area. The land could exist but it would need a desert in that region to make it realistic. Anyway for fun here is the results from a quick run.

Its given me an idea for another parameter to try to fix up the local pools of water. I have obviously got a little problem there that needs fixing. The longer you run it the worse the pooling becomes.