Yeah, the display of deltas depends a LOT on the scale of the map. They usually originate at the ends of wide, slow moving rivers where there is a shallow bed. This gives the chance for river sediment to build up and creating sandbars, diverting the water and further widening the river. The scale of the map will determine how much of the delta will actually appear as a river or collection of water ways around small islands.

Another thing that should be noted is that lakes are almost never the source of rivers. Streams and rivers flow into lakes (at a low point in the flow) and then most often have only one outward flow that moves further downstream. There are exceptions to the one outflow rule when something blocks the original outflow and the lake reaches multiple places that have the same level as outflow. Rare, but COULD happen. This situation will not last long geologically as the softer ground in one location will carve a bigger outlet faster bringing the level below any others.

Another inconsistency is that you you have a couple of rivers that go from coast to coast. Again, this is something that RARELY (if at all) happens in the real world, but there are natural channels between bodies of water. These channels are usually quite small, and much like deltas in that the scale of the map will dictate whether or not they would appear on a map. I think breaking those rivers up and give them different sources would help a lot.

I like the idea of the sun burst, but maybe making it a bit more subdued would make the land stand out a bit more. As is it seems to overpower the map. It might also be worth thinking about using the origin of the burst to indicate the main cultural center by placing it under the main city...just a thought. Keep up the good effort, and as was already stated, map the way you want to map and your own style will come forward. And that is NOT a bad thing at any time.