Okay, first of all, I LOVE THIS, it's beautiful!
But can I add some nerdy, science-y, geographical comments? (Remember, I'm a geologist, so I can't help it!)
Mainly, the equator should be lower. Firstly because right now it's not at the "fattest" part of the globe. :D But assuming that the SotE Earth had similar atmospheric circulation patterns as our Earth (let's assume it does), then the equator should be surrounded by jungle/tropical/humid regions... so on this map maybe at the bottom of where you've drawn the Kashahn jungle, or at least in the middle of it. Deserts occur around 30˚ (north and south), where dry, "cold" air cycles back down towards the globe. All the moist, rainy air rises up from the equator and rains out there.
Science!The rest I guess are little finicky things. :D But if Serendipity isn't a delta system (like Essryn), then rivers typically have lots of branches/tributaries in the highlands/mountains/inland that flow together to form one big river further down until it meets the ocean (where it might splay out again as a delta, but this is a much smaller structure).
Also, I actually think the area around Essryn looks pretty good how it's colored now. Most deserts won't be
all sand sea, and it looks like part of it is now already (color-wise)? A lot of a desert will be vaguely shrubby, stoney, and not entirely covered in sand.
There should also be some band of
taiga or boreal conifer forest before the snowy tundra starts in the north. But that's pretty nit-picky.
But the more important thing is I LOVE THIS. A lot.