Looks really good! But you still have two outlets from that large SW lake.

One way to justify a broad area of lava cracks if you still want that, is to assume a formerly solid stretch of land is being melted from below. Say, as if the hot spot plume beneath Hawaii was hundreds of miles wide, instead of just a few. That would even explain your mountain as depicted - in a lake of lava, without visible flow from its top like a simple volcano might have. If such heat ebbed and flowed rather quicker than earthly geology suggests possible, you would likely get a pretty barren wasteland - just what it looks like you intend.