Fonstad’s map places Utumno more than 2400 miles (using the scale provided) from Cuiviénen, where the Elves awoke and began their journey toward the West. Notwithstanding the unknown physics of Eä and Arda, would it have been possible for the Elves to hear the sounds from the Siege of Utumno and see the lights (from fires) and great clouds (of smoke?) arising from it that far away?

Based on other observations, we can assume that 1) Arda was flat then so there was no horizon and 2) Elves have far superior vision than other races. Given theses two assumptions, maybe it’s not such a stretch to accept that even from 2400 miles away, the Elves could have seen and heard the Siege of Utumno. If we discard these assumptions then Utumno must have been located closer to Cuiviénen than shown on Fonstad’s map.

> “...the Quendi knew nothing of the great Battle of the Powers, save that the Earth shook and groaned beneath them, and the waters were moved, and in the north there were lights as of mighty fires.”
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>“It is told that when the hosts of the Eldalië departed from Cuiviénen Oromë rode at their head upon Nahar, his white horse shod with gold; and passing northward about the Sea of Helcar they turned towards the west. Before them great clouds hung still black in the North above the ruins of war...”
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> — _The Silmarillion_ by J.R.R. Tolkien