What's this River's name?

[Crel]

Hey all, quick fiddly/obscure question on Esrolian geography. What's the name of the river which runs through Sylthi and Helerdon in North Esrolia?

Per the region's entries in the Guide, I'm pretty sure the left tributary passing through Roskoth is the Malthin river due to matching Longsi Land better and better matching distance (about 50 hexes at 5mi/hex, for 250mi length), leaving the middle and rightmost unnamed in the Guide and Argan Argar Atlas. Do they have names in material I'm unfamiliar with/don't have access to, or is that unexplored?

Thanks!

For reference, page 30 of AAA.

[metcalph]

Esrolia: the Land of 10,000 Goddesses p13 labels the tributary past Helerdon the Whitefall River, the river past Kosh the Hrenal River and the River past Roskoth the Malthin River.

[Crel]

58 minutes ago, metcalph said:

Esrolia: the Land of 10,000 Goddesses p13 labels the tributary past Helerdon the Whitefall River, the river past Kosh the Hrenal River and the River past Roskoth the Malthin River.

Gratitude!